I bought Guitar Hero I for PS2 even though I didn't have a PS2...just because I wanted to try it so bad and there were no kiosks back then. So far, it's gathering dust. I should sell mine.
I think it's because I passed all the songs and got bored of it, tried GH2 as well. I guess the music just doesn't suit me most of the time. What should be good at the user hacked and customized Guitar Hero games you can download and burn onto a DVD...with all sorts of music. There's like 80s guitar hero and techno guitar hero, etc. I think, I haven't gotten around to trying them though.
Guitar Hero would be so much more fun if they could find a way to put rows of buttons on it like a real guitar. You might not believe me, but it's actually much easier to play 2-4 rows of 4 buttons stacked than 1 row of 5 buttons. Also, I HATE ORANGE. The buttons just aren't intuitive to me and I can't get a feel for where my hand is ever...since the buttons are bubbly and smooth. I would love a guitar hero controller that actually has sunken buttons like frets on a real guitar so you know where you fingers are at all times.
I also don't like the flappy paddle thing you use for the strum bar. It's too chunky to use comfortably, they should have something thin like a metal wire so it's more like a guitar string. Also, I play with a guitar pick on the GH controller, makes it easier it seems. But I guess my version of a guitar hero controller would be slicing up kid's hands or something