It's always interesting to see what John Carmack has to say, and his recent interview regarding the iPhone and Doom Resurrection is no exception. I went ahead and bought Doom Resurrection on my iPhone, and I have to say, the tilt controls work surprisingly well. I'm actually enjoying it, which is more than I expect from most tilt-based games.
Graphics are pretty snazzy too, shooting zombies just feels right, and there's even some humor and charm courtesy of your companion robot. I dare say it may be worth the $10.