I have GH2 on 360
Its pretty fun. But its one of those games that takes LOTS of practice. I've just about mastered Medium, and will be trying to start with Hard sometime soon.
I've also played GH3 on 360. The GH3 guitar is MUCH better quality than the GH2 one. And the track listing has a lot more original songs rather than covers, which is nice.
If you don't mind spending hours and hours failing, and practicing loads, and like to think that you are playing a guitar, without actually having to, its a good game. its a good laugh at parties as well.
Otherwise... stay-away.