Certainly one of the iPhone's most-used features is the camera. There are a huge number of camera apps available, and I certainly take more photos than I make phone calls.
The iPhone camera doesn't compete with a dedicated DSLR, but it is among the finest camera phones there is in terms of picture quality.
With iOS 8 there are quite a few new features to enhance your photography. Some of these features have been available in other apps, but all of them are nicely integrated into the stock photography software Apple provides.
One of the most interesting new features is what Apple calls 'Smart Composition Tools'. These features, when activated, will automatically straighten horizons ( a big problem in many photos) and do some smart cropping.
After you take your photo and notice the horizon is tilted, you enter the edit mode and select the crop tool. IOS 8 will make a pretty intelligent guess about how level your camera was, and make the edit instantly. You can also adjust this manually, so you can tilt the image if that's what you want.