It was a step back from iOS 10 on older hardware. I upgraded an iPad Air and iPad Pro first gen and the UI stuttering/stalls makes both machines feel slower. I decided beforehand not to even try on the 5S, which was a good decision except that Apple constantly nags to update and downloads the entire 1.1 GB update file to my 16 GB device without asking me (yes, I have background App updates turned off) and forces me to delete it manually to get storage back. It's infuriating.