MMOs are a weird sort of thing. Some portion of the players want social interaction in virtually every aspect of the game, while others want to do their own thing for the most part, with the option of fiddling about with social interaction when it suits them, or as necessity demands. I fall into the latter category myself, as I play MMOs as single player games, except when it comes to three things: Trade, PvP, and Dungeons. From what I've seen in the first 20 levels of The Elder Scrolls Online, it seems to cater to my style almost exclusively. It's not as exciting as it sounds, though, as MMOs absolutely need to recognize that they're multiplayer games in order to function, and TESO likes to forget this fact.
That's not to say that TESO is anything short of a great game and stellar experience. By the time you hit level 20, you'll likely enjoy playing through well over 100 quests, each of which has fully voiced dialogue and even occasional moral choices to make (although I'm skeptical that your choices carry any weight in game). You'll probably do dungeons in a small group, PvP in Cyrodiil alongside dozens of other players, and even explore entire continents all by your lonesome. What's odd, though, is that throughout all this, despite the constant banter going on in Zone Chat, you'll rarely feel connected to the other players. TESO feels a lot like a multiplayer Skyrim mod. It seems to have been designed as a single player game, with the multiplayer content being tacked on, but still exceedingly well done.
Starting with character creation, the detail put into The Elder Scrolls Online is uncanny, which should be no surprise to fans of the Elder Scrolls franchise. Between the ten playable races and a seemingly endless supply of appearance customization options, you'll be able to create virtually any look you want in game - from reptilian Argonian to sleek and furry Khajiit to your standard, stoic almost-human. Each race comes with its own unique traits, as well as racial skill trees to sink points into as you progress through the game. If you're any kind of min/maxer you'll do well to check out your race options before committing to a race/class combination, to ensure that your racial skills complement your class choice. Classes are fairly minimal in The Elder Scrolls Online, with only four options available; Dragonknight, Sorcerer, Nightblade, and Templar. Though that may seem restrictive at a glance, the open system for skills in game will allow you to tailor your character to your own playstyle as you level up to some extent. It's not quite as open as Skyrim, though, since you're still restricted in what abilities you can develop and use by your initial class choice. You can't play as a Nightblade and decide to start summoning Daedra minions like a Sorcerer. You can, however, play as a tanky sort of Sorcerer with heavy armor, sword, and shield. You'll still never really be as good a tank as someone who chose a tank class, but the option is there to tinker with if you so choose.
Once you get past character creation - something that'll take some players a minute and others an hour - you'll have to run through the tutorial. Taking you to Molag Bal's plane of Oblivion, Coldharbour, TESO begins its story in true Elder Scrolls fashion: escaping imprisonment. After learning how to move around and swing your weapon, you must help an old man known as The Prophet escape from his cell. He will then in turn help you pass through dimensions to escape Coldharbour. This is the first of the main story quests which, up to level 20 at least, all revolve around The Prophet. Unfortunately, the main story quests are fairly sparse, with a new quest only becoming available every few levels, with each typically lasting 20-45 minutes. They can be a little irksome, too, with unskippable non-cinematic animations sometimes dragging on for several minutes, like when you're asked to follow The Prophet for what seems an eternity, as ghosts of the past banter amongst themselves. This is going to be a treat for the sort of player that reads every lore book they encounter, but if you're trying to get to the end game as fast as possible - or simply don't care about the story - it can be quite trying. Even with the story being more or less forced upon you, they're still typically fun to play through, often taking you into the past through the perspective of another character. It's a great twist on storytelling - allowing you to experience the story, rather than just read or hear about it.
The Elder Scrolls Online doesn't believe in quest hubs like you may be accustomed to from games like WoW. While it may be slightly frustrating for the most serious power levelers out there to have to go out and find the quests they need to level up, these quests are fairly bountiful and sufficiently interconnected to keep you from having much by way of dry spells. From level 1-20, you'll typically have no less than three quests at any given time, sometimes having as many as 8 or more. Whether you consider this a pro or a con for TESO as a whole, the fact remains that this is something of an innovation for MMOs, and still executed quite well, which is laudable. As long as you're not ignoring Points of Interest on your compass in a rush to complete your active quest, you'll rarely find yourself with nothing to do. It's fun and engaging to have to explore for your quests, but like the unskippable and un-AFK-able story quest animations, there could just as easily be an option to grab quests the old fashioned way, ie. En masse.