I have been using for a few weeks now the PureShot camera App for my iPhone5, and i have got to say it is by far the best camera app i have ever used. It has some nice features and it feels like i'm using a camera not a smartphone :) If your not a fan of compression artifacts you can take advantage of its dRAW output as a TIFF file and even compress to lossless LZW. PureShots Anti-Shake feature is also perfect for improved quality shots, i have noticed all my images are pin sharp !!
You can check it out at the App Store
This photograph was one of the first photographs taken with the the PureShot App using its dRAW setting, you can see more of my iPhone photography on my portfolio website www.iandavidsoar.com