This is exactly backwards - all of the iOS 7 complaints I've heard so far have been about the UI polish and not the underlying functionality. Polishing a turd would be a beautiful UI in front of a buggy, slow system. Apple didn't ship a polished turd, they shipped a rough, unhewn diamond.
But each major iOS version is slower than the one before, it's just that we got used to it (and loud people on the internet always use recent devices anyway). I think this blog post is a good example of something that is definitely a polished turd. A clean, beautiful UI for a resource hog:
And something else that we have accepted is that Apple's services are what they are. For example, iOS 7 has polished the Photos and Camera apps. But in the big picture, Apple's ecosystem for photos is still a complete mess. There is Photos.app with its own Camera Roll, iPhoto for iOS, Photostreams, Journals, Moments, iPhoto '09 with its own Events, and no sane way to keep everything in sync.
If the stopwatch timer didn't record time properly, I'd see where you're coming from. UI polish isn't going to make fix an error in the timer. But here, all the core functionality works, the clocks show the right time, the stopwatch starts and stops. The main complaint here is about the colour of the buttons, which I agree could do with some polish.
I've just installed the update, and the inconsistency between the countdown timer start button and the stopwatch start button are probably deliberate. I didn't think about it at the time, but starting and stopping a stopwatch should have as precise a timing as possible, adding a fuzz of a "pressed" state for buttons which can respond instantly will reduce accuracy of the stopwatch. But for the countdown timer, accuracy doesn't matter so much, and these buttons work like normal ones, with a pressed state.
So, rather than evidence of bad design, this could be evidence of good design.
I wasn't making a judgement, I was responding to the above comment about the BlackBerry 10. iOS7 is great, and I think this article describes polishing a diamond.
Stanley Kubrick "You can if you freeze it."
http://everything2.com/title/Kubrick+polishes+a+turd