Went last year and recently upgraded phones. Noticed my hidden mickeys had been wiped.
I suggest using the iCloud APIs so that it is easy to use between devices and restore info. For example I enter one on my iPhone and can view it later on my iPad.
Edit: no iPad landscape support and not iPhone 5 optimized. Last update was 9/12 -- not a good sign!
This is the type of app that one would imagine needs fairly constant updating. For example there have been new attractions and park areas added since 9/12.
Would be cool to be able to take pictures of mickeys found and have linked to an account and uploaded (with private or shared setting options) in addition to being saved to camera roll.
After trip one could then go through the photos of their mickeys streamed into the app if they have removed the pictures from their phone.
Additionally would be cool if there was some ability to crowd source data, share the pictures as hints (could be good for people having trouble), add new mickeys, etc. -- basically use the people using the app to improve its data.
Good luck. Generally its good, had fun using it as it was helpful, just has a lot of room to grow.
AnchYou about Hidden Mickeys: Disney World, v3.0.0