Having received Guitar Hero 3 for Christmas ( my son that is) and watching my son and I take turns trying the be the next Jimi Hendrix. I started looking at the game "Rock Band", mainly because it comes with a drum kit and and microphone in addition to the guitar like GH3. Its great because you actually get to participate together, just like a real band. I am of course the singer! My son the drummer. Its great because the drums are very much like playing real drums and it helps my son practice some skills for his real instrument.
We start as a lowly band that has no fans. As we get better we get more fans and $$$ to buy cool outfits for the lead singer! :-) There are tons of songs on this game and its about the most fun I have had with a video game. Most of the fun is that I am doing this with my son and both have huge smiles as we try to get the song right, and also its fun to just tap into your inner rock star thing!
If you get a chance to try it out....Do it!