It's a ton of fun, I love it. I'm still working my way through the game on Hard, having never played Guitar Hero/etc. before, but it's worth it and it's awesome at parties.
I recently got the
Omega Pedal to replace the stock pedal for the drum kit. You don't need to go and buy the Omega Pedal, if you're ambitious you can get a kick pedal from a local music shop and mod it yourself, but it's a huge improvement over the plastic one that the game comes with and it makes playing the drums on the harder difficulty sections much easier.