I can say, without a doubt, that Super Badminton 2010 is the best badminton video game I've ever played. Then again, it's the only badminton video game I've ever played. Still, Indian developer Rolocule has done a pretty excellent job on the game. I don't know how much it actually relates to the real life game (I don't think I've ever played a whole real life game before), but the controls are responsive, the graphics are just about right for the iPhone, and the back and forth tennis-like gameplay is a lot of fun.
There's an awful lot of game here, too, with multiple players and modes to choose from. It's pretty easy to master; just move your player where the shuttlecock is headed and time your hits. Added features (like a tilt function to aim shots and a really powerful smash that requires expert timing) give some nice depth to the gameplay, and multiple tournaments to play through will put your skills to the test.
I only wish the app had a free version available; while I'm sure that the game is worth US $4.99 to those who are in the right mood for it, a trial version with a game or two to play would help potential customers figure that out quickly. If you're on the fence about this one, it's probably best to wait for a trial or a sale. However, if you've been craving a good game of badminton (for some unforeseeable reason), Super Badminton 2010 is a nicely done App Store title.