I am not a big fan of camera effects for serious photography. However, when it comes to mobile phone camera I think effects are great fun to use.
Here are two Android apps that will please many photographers. Both are downloadable as free apps, or you can pay a small fee to get the most out of them. What I like about them is that they allow you to shoot in silent mode, and they each have a rich choice of effects that you can use to soup up your shot. Each has its strengths and weaknesses, so I recommend you download both.
Camera360 lets you choose the effect before you take a shot. As an example of what it can do, see the image that shows I have been painted by a street artist in Europe.
Little Photo, on the other hand, lets you take a shot and then enables you to choose which effect you want to apply on the image. The portraits below show what the shot looks like before and after applying one of the effects.