Let me start by saying one thing : This is a BETA? Minecraft is already robust and rounded out enough to be a full fledged game, and I doubt anyone could complain. This game is meant to inspire everyones inner architect, and possibly inner child. I can think of a million reasons to not like minecraft. The graphics are intentionally pixelized, the enemies can be annoying while building, theres no story, no gameplay goals, etc.. But all of those are thrown out the window (well, mostly) when you really start to get inspired and tinker with all the toys at your disposal.
Let me be honest - I didn't like Minecraft until I realized all the crazy things I could build. Why go shoot faceless Mooks one after another when you can ride a pig off a cliff into a pool of lava, while eating chicken? The game offers tons of fun if you know where to look for it. Giant pixel art, multiplayer mahem, fun with fire, and, for those other people, possibly giant [Instert something I would not like to mention here]s. Theres no predefined goal - Its just you, a world 8 times the surface area of earth, and those damn creepers.
Minecraft isn't for everyone, sure. But the gameplay is what you want it to be. Maybe.. build rollercoasters? Build scale models of real-world buildings? Complex machines that constantly kill monsters? Or if you're not that creative, maybe you could just go set a village on fire or something. I dunno. Minecraft is a game about imagination, and if you don't have much of it, you probably won't find much fun here.
However, the one glaring problem I see in Minecraft is, believe it or not, boredom. The game is a blast.. while it lasts. After a while, you may slowly become uninspired and decide to call it quits for a while, only to take a long break from the game that slowly evolves into a month-long hiatus.. I'm not saying this will happen to everybody at once, but boredom will grip you eventually. Also, the combat is dull at times, with each enemy being incredibly predictable eventually. But does this make the game any less fun while it lasts? Heck no!
And if you DO get bored, why not try some of the other things, or challenge yourself? Build a stable house in the Nether? Try out the freakin' epic Multiplayer? See just how ABSURD your creations can get? Minecraft is epic. Buy it.
Just watch out for cree - *pchk* ssssSSSSS - *BAM*