Inexplicably, all of my iWork documents in iCloud were deleted today, EXCEPT for one Pages document. No one touches any of my Apple devices except me and they're all password protected. I didn't delete anything from any device. Fortunately, I have two versions of backup, one in Time Machine and another in CrashPlan, so I was able to recover everything. But this has shaken my confidence in iCloud. The iWork apps all sync beautifully with one another and the implementation is far more elegant than anything else I've seen. But the one fundamental attribute of a cloud-based system is that data should be secure. And clearly that's not the case here.
I'll continue to stick with the iWork apps given that I have good backup solutions. But, if this happens again, I'm going to try something else.