The 5 frets down hear the body of the guitar are used for solos only in Rock Band. It's just a gimmick.
Supposedly a very fun one, though.
True, I don't think they are going to function in GH3. It is a much nicer guitar though.
The RB guitar doesn't work in GH3.
I just finished the game on medium, and... it's decent. For some reason, I just didn't enjoy it as much as GH2. For whatever reasons, the songs just didn't grab me... it could've been because I was blazing through it, though.
The graphics (lol again) somehow look worse. It doesn't help the art style that I really liked that it was lighthearted and cartoony in GH2, but it got bastardized and had some grittiness mixed in... and it just doesn't look right. Of course, the interface (which is what really matters) definitely looks better and cooler.
The notecharts are good for the most part, there's a few bad eggs though (like Barracuda), but some good ones too (My Name is Jonas).
The tracklist is obviously very good.
I guess I'm just disappointed with it. I mean, it's definitely fun, and I don't regret buying it (wireless guitar FTW)... but it doesn't have that "thing" that made GH2 so great (in my eyes at least).
That's just my 2
¢ of the whole thing.