I've been considering getting Guitar Hero 2 for my Xbox 360 for some time now.
It's the $100 price tag that seems to turn me off everytime.
I've heard that Guitar Hero 3 will be out sometime in the near future.
It will feature Slash from Guns & Roses and the guitar will be a Gibson Les Paul.
Sweet!
Here's a link for more info:
http://en.wikipedia.org/wiki/Guitar_Hero_3