I'm not really a gamer, but this is just so much fun. Friends of ours have had Guitar Hero for their PS2 for quite a while and it just doesn't do anything for me. But I absolutely LOVE the drums in Rock band. Singing can be fun too and I even like the guitar better than in Hero.
I have to admit I really got a kick out of creating my own character. In addition, the music is great. I was very glad to see that they made the drum set adjustable and I like the two sets of keys on the guitar. I also think that the notes are easier to follow on the screen than they are on Hero. I was a little unsure about the price tag at first, but it has been well worth it, I have to say. My one criticism is what I suspect everyone else is saying: Where's the bass? I'll be glad when they come out with guitars sold separately, but I'm concerned they'll be priced through the roof, which would be a major disappointment.