Recs.
Updated
Instagram (free - no IAP) is a very popular photo sharing service, with apps on both Android and iOS IG has a huge community.
Specs
Pros
Pro Fun Filters
Instagram for Android offers seventeen different filters that can be used. These filters can be used in many different photographic situations to add dramatic effects and fix some common exposure problems. Instagram filters are very easy to use and make editing photos fun. Each filter can be applied on a scale of 0%-100%.
Pro Huge and Enthusiastic Community
The Instagram community started with the iOS version of the app. It grew to a large number of users before adding an Android version later on. Never a shortage of interesting photos to look at and photographers to follow, as well as being very easy to share your photos with the community and your friends.