Yeah, Rock Band is not much of a challenge when it comes to the guitar. You are 100% right that they're more for party gaming/fun; Guitar Hero is the series you play when you are an expert shredder. RB2 is slightly harder than RB1 I guess but still, I haven't failed out of any songs yet (although the solo on Man in a Box was pretty tough). I'd honestly stick with drums for single player.

Rude, you HAVE TO go back and beat that final level of Braid! It's really not that hard, certainly compared to what came before (you just need to do things as fast as possible) and has a VERY cool ending. Then you gotta go back and get all the secret stars! Including the one that takes 2 hours to get... /sob