There are a few legitimate problems on iOS7 on 5S.
- buggy with iWork apps... very soon to be replaced so no big deal at all
- my 5S crashes at least once a day, and that's not acceptable to me, but it's probably just problems with the 64 bit architecture, so it'll probably get soon better
- inclinometers badly aligned. I'm lucky mine is off by just one degree in one dimension only, so I can still use it the other way, or just subtract the degree. This is the biggest...