I think the re-release has blue buttons instead of green, other than that, it is identical to last year's release (as far as we know).
Is it worth it? Of course that's a highly subjective question.
I bought an xbox just to play it last year simply b/c I know it is one-of-a-kind experience. And it did not fail to live up to that expectation. It is a mech-simulator.... simulating an experience that does not exist! You are basically thrown into a war zone controlling these huge mechs destroying everything.... You have an unprecedented amount of control over your mech, you will be multitasking, you HAVE to multitask to succeed.
It is intense, it is realistic (or supposed realism), it has excellent graphics, unbelievable sounds and superb control.
And it is hard, it will kick your ass over and over and you will come back for more if you like hard games.
But it is not for everyone, certainly not for someone looking for a quick pickup and play kind of game.
I can't wait for Lines of Contact so there is team play. Yes, I will get XBL just to play this game.