I've had a few. Once was in the camera app. Just had to do a hard reset with home button and power button pushed down. I can't remember the other time. But things just froze and we're unresponsive. Hope it's just the newness of the OS and not my 5s.
The photos app crashed out on me after I deleted 114 photos in one operation. Relaunched it and it did delete the pics and nothing seemed awry. Growing pains I guess.
My camera app has crashed a couple of times along with various other "iOS 7 updated" apps like Twitter and Facebook. I've only had the device reboot once though (iphone 5s)
Yea it refuses to function on my 4S since the iOS7 update so I just go through Safari.
But I am considering setting my phone up as new, and NOT restoring from a backup at all, and then going into the app store and just downloading all my apps individually so I can control what I put back on the new one when I get it. As a deliberate action to hopefully prevent whatever issues I had plaguing me forever on the 4S's from carrying over. I can d'l any pics I need/want from dropbox.
I'm quite impressed with this phone (5s). Has been top notch. I had the 5 and that thing did have some slight hiccups at times. I have sprint and in Miami sprint has deployed their LTE all over the place. I had the 5 since launch just like now I have the 5S. Comparing this week performance from the 5 to the 5s with sprint LTE. On the 5s I'm getting extremely better LTE and constant speeds. I'm assuming this is because of the better LTE radio.
I've had a flawless iPhone 5s white silver. No crashes. Just infinity blade 3 crashed the first couple of times I started it. But offer than that I'm happy.