There are reports circulating (
MacRumors,
MacIssues) that data in your iCloud Drive [ iDrive? ] may get erased if you choose to Reset All Settings" in iOS 8. The screen you will see states that 'no data will be erased' but people are reporting that at least their iWork files are being deleted.
I'm not using iCloud Drive (knowingly) nor do I use the new iWork apps that save their files there. There are a couple of solutions to prevent this possible loss:
1. Don't use iCloud Drive yet
2. Make sure you have easily available backups of anything you store in iDrive
3. There have been warnings about Yosemite Beta testers using iDrive, none of them should complain if they did not heed those
4. There are ways to access the data on Time Machine by using Finder instead of the TM interface
Hopefully, this will be similar to the iPhone 6 'flexibility' problem... Otherwise, look for an update very soon!
