OK, I've played it a bit and my conclusion is basically the same as this review - it's a fun game that does some things differently in an interesting way and is easily worth the price, but has some serious flaws that unfortunately drag it down.
By far the biggest problem is the interface and information, or rather lack of it. The tutorial is actually very good at introducing the basics of the game, far better than in most games in fact, but that's where it ends. There is no manual, only an incredibly half-arsed and completely unfinished wiki. If you want more detailed information about exactly how a particular mechanic works, or want to know where to find a particular bit of information, tough. The only option is to figure everything out yourself. In many cases, what you'll figure out is that the information simply isn't available. For example, information about planets is heavily focussed on the export and levelling system. If you want to see a nice pyramid display of how all your planets are connected and what level that gets them to, you're good. If you want to see which ones are actually capable of producing anything or where it might be a good idea to send some new goods, the only option is to click through every one individually and hope you remember the names by the time you're done. The same is true for all aspects of planets and resources; there is no way to find out which planets are important for producing research or which might be lacking in defending ships other than manually looking at them all. Given the scale of the game (I started with a fairly small game on easy, and controlled over 40 planets after about an hour of play), this is a big problem, and will only become more so if you want to make use of the large scale the game allows.
Other than the frustrating lack of information, the game is mostly fun. The pyramid-type networking of planets is a very interesting idea that makes strategy very different from the usual 4X. Instead of having a whole bunch of well established planets (or cities, or whatever) as production and economic powerhouses while newer border planets are little more than a buffer zone, every planet is important. Production and resources will be focussed on very few powerhouses (in the above mentioned game with 40+ planets, I had one level 5 (the maximum) and three level 3), but losing a single level 0 planet can bring down the entire chain. Fortunately this is one area in which the interface really does work, and it's easy to see which planets are connected to which others, and to juggle things around to optimise things and reduce vulnerability to a quick strike.
The movement system also works well alongside this. While there are different "FTL" technologies (all movement is clearly ftl, even though basic movement is referred to as "sublight"), all ships of all races can fly directly from anywhere to anywhere else with no restrictions. This means attacks can happen anywhere and you need to be ready to react to this, and different races may require different strategies. The basic hyperdrive can also go anywhere with no restrictions, faster than normal travel but slower than any other ftl types, making it reliable on attack and defense but possible to work around if you're careful. There's a gate network type that is great on defense but useless for attacking, and the reverse in flinger technology that can throw ships anywhere at high speed but can't bring them back, and finally a wormhole tech that gets you between any two places instantly, but leaves the wormhole in place for a while and can be used by your enemies as well. On top of that, FTL energy is an empire-wide resource, so you need to be careful not to use too much up and leave yourself unable to respond to an attack. It's an interesting strategic system, the only choice missing is the ability to turtle up and be fully defensive, as is usually possible in games that restrict movement to fixed lanes.
Combat is fun, but perhaps not all it could be. The problem is the tech tree, the ship designer, and the nature of battles. The problem with the tech tree is essentially that it's boring. Almost everything is simply percentage upgrades to existing things. The final screenshot in the review shows the designer, and the list of weapons there is almost every weapon in the game, most of which you have access to from the start. There's no race to develop better weapons, and not really any kind of rock-paper-scissors system, there's just lasers, railguns and missiles and a couple of variants that hardly differ. Which brings us to the nature of combat - fleets consist of a large flagship accompanied by a whole pile of smaller support ships; a few tens of them early on, potentially hundreds later in the game. You can have as many fleets as your economy will support, but you're effectively only controlling a few units at any given time (in my game above, I only had 5 fleets by the end). Movement is newtonian and fairly slow, so there's no possibility for fancy manoeuvring and tactics. Unless one is significantly faster and run away, fights consist exclusively of sitting next to each other and pounding away until only one fleet is left. This makes designing ships almost entirely pointless. You'll be fighting hundreds of ships with a selection of all weapons and all defenses from the start, so there's no possibility of picking specific weapons to counter your opponent or anything like that. Fancy design and tactics like shield ships as described by Jonathon above might make a small difference in marginal fights, but the vast majority of fights will be decided by one person bringing overwhelming force. Combat looks amazing, and the movement system makes deciding when and where to fight a fun part of your strategy, but once ships are engaged it's all about who brought more guns, with the design part of the game being entirely extraneous.
Edit: I should add here a mention of supplies and planetary combat. There is no ground combat, planets are captured by fleets and they need to spend supplies to do so. Supplies are provided by supply modules on the flagship (in theory you can put them on support ships as well, but requires maintenance costs that they don't normally have, and will only be tiny amounts compared to the flagship anyway) and are spent by firing weapons and capturing planets. They regenerate in systems you own, as long as they're not contested. This means you can't simply send a powerful fleet out and march steadily across your opponent's territory, after a couple of captures you'll have to return to resupply. It also means that throwing small fleets with no hope of victory against an attacker can reduce their supplies enough to prevent them from capturing anything at all, so suicide and guerilla attacks are a useful defensive strategy if you can't win a head-to-head fight. A fleet low on supplies will also have reduced combat effectiveness (presumably reduced damage and possibly speed, although again the information is rather lacking). But, in contrast with a game like Space Empires which could completely strand your fleets and leave them unable to move or do anything if you didn't micromanage them, they are never completely useless. Supplies regenerate automatically in your own systems (faster if you build stations to support them), so its a matter of not overextending your reach rather than an annoying micromanagement chore. This is probably my favourite supply model in a 4X, definitely better than artificially restricting range, requiring micromanagement, or simply pretending logistics isn't an issue at all.
The tech tree also has issues with more than just combat. As noted, almost everything is just incremental percentage upgrades, with very little in the way of unlocking new things to build or do. Ringworlds get mentioned a lot, and are right at one end so I haven't tried them out. Planetary thrusters allowing you to move your planets around sound interesting. Shields are the only reason to ever use the ship designer (basically you want one set of designs without shields, then another set with shields once you've unlocked them). I can't really think of anything else that isn't just a basic upgrade or minor variant on something you already have. Tech is important, since the upgrades really add up, and it's possible that there are specific unlocks that are useful for particular goals or play styles that I haven't found yet, but for the most part it's just completely lacking in character.
And that's where I think the game will suffer in terms of replayability. There's no effort whatsoever to fit any part of the game into a fictional universe. 4X games don't necessarily need a plot and individual characters, but they need something that makes it more than just red team vs. blue team. I have no idea what the races even are; the only time you see them is a single still picture on the selection screen at the start of the game. In the couple of games I've played so far, my opponents have been colours and nothing more. There are some slight mechanical differences in how they develop planets, but other than that there's nothing to distinguish them and no personality at all. Coupled with the bland tech tree and lack of any meaningful customisation of ships or planets, there really is just noting memorable here at all, and nothing that will actually immerse you in the game or make you identify with the game. The blue border expanded until the red one was gone, and I have no idea who I was, who I fought against, or what crazy futuristic technologies I used to do it.
Getting back to the good points, the diplomacy system is by far the best I've seen in any game, bar none. There are actually two aspects to it. The card system gets the most focus in reviews, but there is also a more standard system as well, allowing basic alliances, trade treaties, and so on, that AI players will agree to or not based on shared borders, attitude, aggressiveness, and so on. Even that part on its own works as well as the whole diplomacy system for most games, but the card system is where it really shines. There's a global pool of cards for all empires to pick from, with unpicked cards slowly dropping off one side while new ones come in to replace those and any that have been bought. These cards are either things that must be voted on by all empires (such as investigating an empire to give everyone vision on their systems, or moving the galactic stock exchange to one of your planets), vote cards to support or oppose said votes, or actions you can play inside your empire (such as renaming a planet, giving it minor but useful bonuses). Purchasing and playing these cards costs influence points, which are generated as one of your resources in the same way as research and energy, although a few can cost money or energy instead. This makes for a very interesting system. Cards in the pool start off very expensive, and drop in price as they age before they drop out the pool entirely. So you might want to jump in early to get a card at a high price either because you really want it, or just to stop anyone else having it. In particular, since voting cards are limited, it's possible to buy them all up while baiting everyone to use theirs up in preparation for pushing through a vote you really want. And since annexing planets and entire systems diplomatically is possible, this finally gives us a 4X game where diplomacy is seriously meaningful. No amount of firepower can save you from someone who manages to manipulate the diplomacy system to steal one of your key systems, and they won't even need to go to war with you to do it. Best of all, the AI engages in diplomacy both actively and competently. They won't blindly turn down treaties and oppose everything the player does, they'll propose sensible things, vote to their benefit, and not vote when the outcome doesn't interest them. You can use the system to support your economy and war efforts, or to aggressively expand your borders without firing a shot, and the AI will do the same right back.
Overall, it's a good game if you're looking for a 4X that does things a bit differently. The planet resource and levelling system seems to annoy some people, but it's an interesting twist on the usual way things are done and really changes the strategies you need. Combat looks very pretty and and the higher level strategic side is fun, but design and tech is poor and actual fights are little more than "who has the biggest gun" competitions. Diplomacy is simply amazing. The game will likely be hard for some to get in to due to the lack of any useful manual and the often frustrating interface and lack of important information, and replayability may be lacking due to the extremely bland tech tree and severe lack of character and background and world building in the game as a whole. It's not going to go down in history as one of the best games ever, but at around £20 full price it's definitely worth the price for fans of 4X games.