Minecraft for the PC is so much better but if your computer can't run it then I highly suggest getting the Xbox version. It's a lot of fun and a great way to kill time when none of your friends are on.
Absolutely Worth it. I got it back in October of 2010 and I still play it, it's timeless and updates come out frequently to suck you back in after interest is lost. And you can't beat playing multiplayer with a bunch of your friends because there are so many possiblilties for things to do . I am of course talking about PC.
If you enjoy having fun, then yes. Yes it is worth it...
But seriously it's a great game, and for the Xbox I found that for the most enjoyable experience grab a friend for two and play on HARD Survival without any mods or cheating. Same thing with the PC, playing on HARDCORE PvP servers can be a real blast!
Definitely. Currently, the Xbox version is basically a watered down version of the PC game. But updates are coming swiftly and it may soon rival its PC counterpart, which is an absolutely amazing game.