Is Mental Case ready for iOS 8?
Mental Case is working fine on iOS 8, however, there are changes in iCloud that you should be aware of before upgrading.
Apple are introducing iCloud Drive in iOS 8 and Mac OS X 10.10 Yosemite. iCloud Drive is not compatible with iCloud on iOS 7 or Mac OS X 10.9. Once you upgrade to iCloud Drive, it will no longer exchange files with iOS 7 devices and OS X 10.9 Macs.
What this means for Mental Case is that once you upgrade to iCloud Drive, you will only be able to sync your iOS 8 device with other devices running iOS 8 and Macs running Mac OS X 10.10 Yosemite. Only upgrade to iCloud Drive if you upgrade all your devices.
Note that this applies to all apps using iCloud, not just Mental Case. It is the result of Apple changing how iCloud works.