I've got GH3, I bought it shortly after it came out, I play with a standard controller though, due to me not having a guitar controller other than the one my friend broke the day I got it.

I've primarily destroyed Easy and Medium, 5 staring everything, about 90% through Hard with about 50% of that 5 stared, and about 5 or so songs into expert, a couple 5 stared, 1 100%'d. My friend got the 360 version the other day, we played through co-op on medium, he sucks.