You can add an HDR-style effect to the image, whereby the darker areas appear brighter and the bright areas appear darker - giving your image more dynamic range. This gives you an image which looks more akin to how the human eye sees it, rather than a camera.
Filters allow you to apply effects to your image with one touch, usually with a range of effects such as retro films or sketches.
You can apply a mirror effect to the image, allowing you to experiment with creating symmetrical images.
When taking a picture with the app, you can preview your next photo with the filter already applied. This means you can choose a filter that compliments the scene before you capture the image, rather than applying it later.