My buddy and I have just played Rock Band for 4 hours straight since I got home for work. I definitely like it better then Guitar Hero. My buddy sang and I played the drums and then he switched over to the guitar. It's definitely worth the money. Although I had a hell of a time setting up the drums. The stand is pretty cheaply made. The guitar is definitely a better then the GH ones however not being wireless makes them about even (I got it for the 360). The drums are pretty intuitive. I started out on easy and ended up moving on up to medium. I can't wait to get more friends over to have a whole band.
