[quote name='phutu']anyone who played the game and the real thing: how similar is the experience?[/quote]
Having never played the drums before actually getting Rock Band (I tried DrumMania with the home controller, that nosedived quickly), I'd have to say it's a fun experience. But it will probably only teach you the basics of drumming with simple and even beats with consumable time signatures.
It taught me a LOT about leg/arm separation and how to "feel" a beat with my foot as my leg would just spaz out whenever a flurry of bass notes come up. After playing the Expert level, I've been able to play simple beats on my friends kit, but nothing advanced. You'll probably learn some good basic beats that will get stuck in your head and you could do them in your free time, but you're not going to learn accents, polyrhythms, and all that other stuff by just by playing this game.
But the bottom line is, it's VERY enjoyable and satisfying as the drum kit actually represents the actual instrument (it's basically a very bare-bones electronic drum kit) and makes you hone your timing skills and such.