Occurro is, I would say, an above average space-based dual stick shooter for the iPhone. It doesn't offer much more than an arcade experience, as you pilot a small ship around the screen with one thumb while shooting in any direction with your second thumb. But Occurro is a particularly well-done version of this genre, with controls feeling really speedy and precise, and a few nice touches such as a double-tap screen-clearing bomb and a shield around your ship for a little extra time to play instead of just a one-hit kill.
Occurro actually came out a few years ago, but it's recently been revamped, with new graphics and extras such as multitasking support and Game Center. Plus, as a bonus, developer Acceleroto has dropped the game down to the low, low price of free until further notice. It's definitely worth a grab at that price: Occurro is available in the App Store right now.