It is very hard to get an expressive control in a touchscreen. It's getting more impossible if you are using iPhone. Check out eBoo - Space Adventures which combine a hard puzzler and a frustrating experience. The result is something simple, but rich of experience. Your hero here is eBoo, a square green alien at his own planet. The story begins when accidentally, he joined the planet's army with his undersized spaceship.
After that, you have to finish fifty levels of puzzle. You can use your ship to hit switches, collecting things, and using its magnet to pulls up and drop the weaponry. Most of the levels could last no more than a minute. But it will still give you an intense experience, so don't underestimate it. When I talk about the controls, it works well in this game. There are two icons for left and right movements, and another one for upward thrust.
Actually, the main enemy on this game is gravity, which will pull your ship down of course. You may not hit the ground or wall too hard or it will crack your spaceship. On each level, you will be ranked with stars. Overall, it is a good game for kids, although even adults may be twisted when playing it.