For those of you who still don't know what Minecraft is, seriously, what are you waiting for? Go play it! Minecraft is a game where you are plonked down on a sandy beach, then left to survive. Simple, right? Wrong. To survive, you need shelter, light, and a weapon. For what, you say? For the monsters that come out at night. From skeletal archers to creepy zombies, at the night or in caves you have to be always on alert. When you're not fighting, you're either mining or crafting. There are over 140 crafting recipes to discover, with a very easy to use GUI to go with it. The developer was even kind enough to include a tutorial on the main site, so if you're having trouble, start there.
Minecraft is a really great game. The gameplay and controls in itself are very well thought out; and when you first play it you think "Wow. How can a game that appears so simple be so complex?" ...And that's one thing I commend it for. Minecraft is so much more than meets the eye, and what meets the eye usually isn't that appealing to most people. It took many months for me and all of his friends to convince him to play before my brother actually tried it. Now he's addicted.
The sounds in Minecraft compliment the game very well, from the peaceful music on the overworld to the terrifying 'ambient' cave noises. Notch did the sounds superbly, and they fit the blocky theme of Minecraft so well. The 16-bit textures that cover the Minecraft world complement the theme excellently and the GUI is perfectly simple.
However, while everything about Minecraft at first look seems totally amazing, it has one huge problem that completely turned me away from it. It has absolutely no replayability. Now, you may argue "But the world is different every time!", and that's what I thought at first. But upon playing it for hours on end, I began to realize something. Every time I made a new world, every time I went mining, every time I died, I just went and did the same thing that I'd done a million times before. You start a new world. Oh, look, a slightly new terrain then your last world. Time to go chop trees, then make a base, then go mining, then find diamond, then build. Every new world. You go mining. Place torches, mine ore, avoid lava, fight monsters. What's new?
Just the absolute repetitiveness of Minecraft is what made me stop wanting to play it. Why do the same thing over and over? When you first play it, there's so many things to discover, so many places to explore, so many things to learn. However, once that's all done with, there's nothing left but to do it again. And again. Then again. That is why Minecraft, though an excellent game, no longer appeals to me. It simply has nothing left for me, that is, until Notch releases new content. But nothing game-changing; simply a new block or a new mob.
In short, Minecraft is only fun for a while. Notch did a truly amazing job with the game, and it is very fun to play, but after you play it for around a month it just loses appeal. However, for just 15 bucks, it is very much worth playing. For 15 dollars you get the game and (hopefully) all the updates that come with it. You'll even be getting it at a discount: for the duration of the beta stage, the game is 25% off!
If you don't want to pay, there's also the 'classic' version. This was the first stage of Minecraft, when all you could do was build with infinite materials. The community has even developed mods for the servers, so it's definitely worth trying out.
Play Minecraft here.