For those replying: please explain why you did or didn't like a game; constructive feedback is more informative than a simple "this game was awesome" or "that game was awful."
For those asking: it helps to know what sort of game aspects turn you on or off, and what you already know about the game you are interested in. It's hard to address "is [game] good?" if we aren't sure what you like and don't like, and whether or not you know the basic info about the game (genre, plot premise).
http://www.gamesas.com/index.php?/topic/1084632-unofficial-is-insert-game-here-any-good/
Useful Links:
http://www.metacritic.com/games/ <- useful insofar as you get a large sample of "professional" opinions, as well as many thoughtful and insightful user comments/ratings. Will not guarantee that you will love or hate a game you are considering purchasing/playing. Sometimes contains useful info about game problems that you can ask us here about (i.e. "I read [game] has a ton of bugs/has long loading times, are they really horribly buggy/long?").
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So for those that bought it in alpha, how is Minecraft? I've been watching a "Lets play" on youtube, and the game looks very interesting.