I've seen some say it is for 3rd party widgets, and one state it was showing for apps that are not optimized for iOS 10 yet.
Either way, it's distracting from the overall look.
Personally I like the date the way it sits, however this is going to be totally a personal preference.
I do agree with the widgets should shrink down when no information to display.
My 5s has been running great on iOS 10. Sure I have a hiccup here and there, but this phone is my daily driver (only driver) and I have had no major issues.
Last year it seemed as though we did not see a PB release until at least 2 days after the Dev release. It wasn't until the 9.X betas that they started pushing Dev & PB around the same time.