Besides the convenience, I think the best part about my iPhone's camera is the ability to quickly edit the pictures I've taken.
To edit a photo, go to your Camera Roll and select the photo you would like to spruce up. Tap on Edit in the upper right corner of your screen. Here you'll be given several tools to edit your photo.
The various edit options (from left to right on the bottom of your screen) allows you to rotate your photo, auto-enhance it, choose different filters, remove red-eye, or crop your photo.