I guess its just a matter of taste. I have talked to a couple of real drummers who love this game. I also know some guitar players who love it as well. I get though why it would be hard to go against your normal instincts. Pretty much the consensus is though that this game is more of a blast in multiplayer then solo.
RB is great for wasting a day with multiple players - I wouldn't be able to play for very long if it was just me. Get 4-8 people drinking beer and switching off instruments - it's a blast.
GH is more the single player game.