One could certainly argue that any game in which you have to come up with your own ways to amuse yourself can't be held up as an example of good design. After all, you could amuse yourself in Kane and Lynch 2 by spelling out dirty words in bullet holes or trying to get corpses to form little pyramids. But I stand by my declaration that Minecraft is not a game, strictly speaking. It's a sandbox in its purest form, without even any story or gameplay obligation to drive the experience. I guess I just have a soft spot for lone developers, since I've done a bit of that in the past (and in the present, and I'm currently debating whether to give any reports on what I'm working on in case I get bored of it as well).
Minecraft hits a lot of the right buttons. The discovery of a few solitary cubes of ore is enough to sustain you through all the tedium of carving out an entire quarry in search of it. And I'm impressed at how wide and expansive and compelling to explore a game world can be when randomly generated from what I presume to be a comparatively simple set of algorithms (simple enough for one guy to put together by himself, at any rate). But Minecraft is still a beta, and the advantage of that is there's still time to suggest additional changes and crafting recipes. Here's a short list I've come up with.
A Buggering Tutorial
Mentioned it in the review but worth repeating, Minecraft has probably missed out on a lot of potential long-term users when casual players have played it out of curiosity and confusedly punched dirt for half an hour before getting exploded by green pixel cocks (that was for all those viewers who asked me why I didn't draw the penis comparison in the video, hope it was as fulfilling as you dreamed). In this day and age, people have short attention spans and first impressions count. The "game" really sells itself short by not even having just a couple of text windows reading, say, "MAKE TORCHES. DROP EVERYTHING AND MAKE TORCHES. IF YOU HEAR A RUSTLING SOUND, YOU ARE ALREADY LOST TO OUR CAUSE."
Some kind of ore detection system
Speaking of short attention spans, I hope you like the sound of a stone pickaxe tapping away at a block of the same material because that is going to be the soundtrack for virtually the entire Minecraft experience, give or take the occasional dirt-shovelling solo. Blindly hunting for ore is a rather tortuous process that gets even more demotivating when you know there could be ore just a single block away but you'd never know because you opted to dig the other way. I know the sense of achievement from working hard to create something is part of what I liked, but just a little more intelligence to go on would be nice.