I reviewed the sister application Sophie Cam, and found a really nice filter application that would let you edit and tweak your pictures. SophieLens takes another more immediate approach. It allows you to apply the expected smartphone filters before you take the picture.
That means you can switch your camera into a Lomo 'mint' filter mode and have that filter demonstrated on screen as you take the picture. while you need to decide how arty you want to be in advance (so it's not suitable for the quick snap of inspiration) if you've time to think about a shot this may be a nice creative tool to have in your smartphone box.
Sophie Lens is available from the Nokia Collection area of the Windows Store for Lumia users, while other handsets have SophieLens Pro available to purchase directly