For a while yesterday, my synced bookmarks disappeared from my iPad, leaving jsut the stock bookmarks (Google, Apple, Bing, etc), while my macs and other devices still had everything. But it all came back about 30 minutes later *shrug*
Yes, I've had the disappearing shortcuts issue on my iPhone. But as you can see above, you'll find people reporting these types of issues on the iPhone and the iPad as well, since it's not a hardware issue. Evidently, it's related to iOS 6. There are several workarounds, but unfortunately, not of them appear to be permanent. Hard resetting my iPhone usually fixes this for me, until the next time it shows up, and then I just hard reset it again.
The other day I was having random freezes as well which have completely disappeared since restarting my phone. I guess ios 6 isn't as optimised as believed it to be. Still the best damn operating system on a phone tho in my opinion