iDrummer is a drum simulator that works in a similar fashion to Tap Tap Revenge, yet it tries to be like Guitar Hero. The game has five different buttons to press that give you a different drum sound with each one. Each button has a line above it that the green dots flow down until they're in the right place for you to hit.
The concept works the same way as Tap Tap Revenge, except there are more buttons to press at once. You're also not playing any real songs, you're just playing out drum beats. So while you're playing this game, chances are anyone who is listening will be convinced that you're just practicing for the junior high band. There are multiple difficulty modes to keep you playing it for awhile, but none of the modes produce a song that you would even know.
On top of all of this, you'll need to place your iPhone down unless you're planning on hitting all five buttons at the same time with one had. While possible, this won't be how you play it to start. If you have a 3G iPhone, you're going to experience some movement unless you've got it in your lap. But what's really frustrating is that while playing the game, it feels like the timing is very much off for when you have to hit the right button.
There isn't a trial version of iDrummer unfortunately, so you can't really give it a whirl before purchasing it. But that might be for the best as it isn't going to hold your attention long enough through a demo to actually get you to purchase the full version. If you're really into drumming, and not drumming with a band, just drumming, then this app is definitely for you if you can deal with the beat being slightly off.