Yeah, fun game, I can see why some people would call it dumb, or actual musicians would look down on it, but it's just a game, that's all.
I bought it a few weeks ago cos the price had pretty much halved by then, I always wanted it but I thought it was way too expensive before.
Me and my girlfriend are working through it, she prefers the drums so I usually do guitar, but I find the songs way too easy compared to the Guitar Hero games. When I drum it's a different matter, it's bloody hard! Fun though, and the free bits where you can hammer the crap out of them, I enjoy those a lot. I've only attempted singing a couple of times but managed to surprise myself and do pretty well, even though I sing like a seal being punched in the throat.