It's back okay... but probably you lost the work you was doing. That's unacceptable for me in a device that is sold as a productive machine; I can't rely on a system where I lose my work once in a while.
And that doesn't happen to me in much cheaper devices. I pay (a huge) extra for superb quality.
On this occasion I didn't loose anything...
This is the first example I've really had of this on iOS and it didn't do much other than inconvenience me for 20 seconds.
Yesterday however, my MacBook had El Cap completely pooped itself.
Had a runaway distnoted process, that eventually fixed itself, then all of the sidebar items in finder disappeared, and nothing would save. I'd written a five page report and pages just refused to do anything with it... Ended up having to copy and paste it to email it to my iPad Pro (ironically).
Eventually the MacBook just ground into a huge gridlock, I closed the lid and it just never woke up from sleep. Had to hard reset it, and that's when I did loose work.
It's all relative, and I find that iOS and iDevices tend to be much more rock solid than Mac and OS X.
Edit: spelling.