Apple has collected together some amazing shots taken with the iPhone 6 and 6 Plus. Really quite remarkable.
Some of these have been edited on the phone using other apps. VSCO Cam seems a popular one, which is an app I've never really taken to. My advice for people wanting to take great images with their iPhone is use the tap to focus feature properly, take your time editing with sliders in the Photos app, and do fine tuning with Snapseed.