PureShot, a US$1.99 universal app, takes a very shooting-oriented approach to photography on iOS. You don't process your images here, or add filters. Instead, you just use the tools provided to take the very best picture you can, then process it on your iOS device, or get it onto your Mac or PC and use a dedicated image editor.
I like that approach, because most do-it-all apps aren't strong in every feature. PureShot is dedicated to taking good pictures, and I think it succeeds at that goal.
The app features 2 quality levels for JPEG images, and even something called dRAW TIFF output, which is a TIFF file with no processing by the app or JPEG compression applied. There is spot metering and tap-to-focus, as well as focus and exposure locks. The app supports three-shot burst shooting, and three-shot bracketed exposures. The screen is loaded with information, including the current position provided by your iOS GPS chip, but you can clean up the screen with a tap of a button.
There is even a one-second exposure option, which provides good results in dark places if you can hold the iPhone steady or get it on a tripod using something like the Glif. Aspect ratio can be selected, but 4 x 3 gives you the full resolution of the iPhone's imaging chip.