Rocking out, but not really (4-/-0/2008)
I buckled under peer pressure in December, and bought a PS3, to compliment the new television. After all, what's the point of a hi-def TV without hi-def movies, right? Having played Guitar Hero II at HMV (and Best Buy, and Virgin Megastore, etc, etc), I figured that Guitar Hero III would be a good first game purchase. And at the time, it was. Playing through on easy, and then again on medium, the game is extremely fun, and the availability of additional songs (for a price) gives it more longevity. I don't think many people will have purchased GH3 and been disappointed. Unless, that is, they have played Rock Band.
Rock Band follows the same game dynamic (play notes in time with music), but has evolved and progressed beyond just a guitar to include drums and a microphone. So alongside playing guitar you team up with friends to form a complete virtual band, with a singer, drummer, bassist and lead guitarist. I haven't yet tried vocals and lead guitar together, but I have a feeling it's pretty messy.
Rock Band beats out GH3 in quite a few areas: character customisation, to help put you "in the game", better progressive difficulty (medium on both games is similar, but hard and expert on GH3 are much more difficult than their RB equivalents), and generally more fun - there are fewer people watching, and more participating.
Apart from the RSI from the guitar and laryngitis from singing (one has to know when to stop), Rock Band has it's downsides, too. Firstly, the quality of the peripherals isn't fantastic. Our drum set was faulty on arrival, and a poll on the Rock Band website shows that 70% of respondents had received a faulty instrument. Secondly, we have to purchase a another guitar, because the PS3 version doesn't support the GH3 guitar (responsibility for this isn't being accepted by anyone) and vice versa. I'll probably just end up buying a 3rd-party guitar, which works with both games (but doesn't look as good). Lastly, it isn't available outside of North America yet, which makes finding bandmates difficult.
Apart from that, I'm loving the game. Having always wanted to try playing the drums, and never had an opportunity, it's so much fun to be able to do it in a pseudo band environment.