In general I don't like them. not unless there is either a 4 or 5 year gap AND the game acctualy does something different or revolutionary.
Halo 2 is not very old. So far this seems just like another Halo as opposed to something new.
Of course I could easily be proven wrong once more info about the game is released, but so far, graphics is the only reason why this isn't just an addon for Halo2.
Of course, really, it's on the 360 so right there I won't have anything to do with it, and when the PC, vista only release comes out in 2015 I'll care even less.
And I'll probably still be playing Halo 1 on my XP PC.
On a Swedish chainsaw: "Do not attempt to stop chain with your hands or genitals."