Mappr provides a useful, but at times redundant service to tag your photos with location markers before they are uploaded to Instagram. While the core OS on any iPad or iPhone will do the same, the location settings on Instagram are not integrated with a map, so Mappr allows you to see where all of your photos were taken in real-time visualization. It's effective, but ultimately limited in features.
When you open the app, you can choose to take a new photo or add one from your photo library. It is then automatically posted on the map if location data is available from your iOS. You can then move the pin, change the address, or view the photo before sharing. The share menu is fairly limited, however. In fact, all Mappr does is store your photos back in the photo library and open Instagram so you can manually upload them. No Facebook or Twitter integration means the app is basically a glorified location tagger, something that your phone already does, albeit with slightly fewer options.
The audience for Mappr is limited. It simply doesn't do enough to warrant a download unless you very specifically want to change the addresses and location tabs for your photos before uploading them to Instagram. It does what it promises well enough; but with limited features, it's an app that few will feel the need to download.