We’ve had to write over a dozen server back ends for iOS applications. There is a lot of manual work involved, no matter what platform you choose (we’ve used Google App engine or custom php solutions based on Joomla). There is the code and database development on the server side, plus a lot of code on the iOS side to handle the calls to the server, error handling, etc. It’s a royal pain and something we’d like to avoid in the future if possible.
Parse is a new service that simplifies back end development for iOS immensely – it can take literally minutes to add a simple server side component to your iOS app.
Pricing is free in Beta and looks very reasonable going forward as well.
We recently used Parse to add server functionality to an iOS Math application for YourTeacher.com. The app stores user preferences to a simple Parse object. Adding Parse to our project, testing, and deploying took less than an hour. Performance is good – besides being able to save and retrieve standard dictionary objects you can use Parse to store and manipulate remote files and geo location objects.
They have a very good overview of the integration process for iOS, plus the API is available as a REST service and for the Android as well.