I don't mind flat. The new icons are fine, whatever. But I do take exception to change for change's sake, which I feel drives a disproportionate share of the decisions made by the iOS7 designers.
Fonts, line drawings, status animations, etc; all pencil thin, and as often as not, illegible. Buttons that don't press, or give any feedback at all. White fonts on white backgrounds. Why? I'm all for updating the look of something, but please don't make design the first priority over usability.
iOS7 looks like it was put together by hipster art students obsessed with the 80s New Wave album covers...and they're art students with 20 year old eyes who can discern a 1 pixel progress bar on a Retina display. I sure can't.
And to think they spent a single minute more on the parallax home screen effect than they did on sytem wide font legibility...amazing. The number of emails on the red badge on the email app looks like a rendering error. It's so thin and barely readable, it looks like a scratch in the glass. This is not progress. This is art school masturbation.
I spent 5 minutes updating apps in the App store on iOS7, staring at the blue progress circles...were they getting thicker as the apps downloaded? Were my eyes playing tricks on me? Should there be ANY question as to what the circle is doing? Should anyone really have to squint to decipher its status? All in the name of a cool "fresh" design? Nonsense.
Is a clean Safari screen so incredibly important to the almighty LOOK of the app, that I should now be required to tap 3 more times than previously to access my bookmarks bar? And if the look is so important, why does the jumbled mix of favicons and disjointed text that my formerly tidy bookmarks bar has become look like an afterthought?
Is it so important to maintain a clean look that the camera app no longer allows you to see the photo you've just taken, without exiting the app and opening the photos app (which has traded traditional simpllicty and quick navigability for an unintuitive, confusing, but oh so "clean" and trendy visual overhaul).
In too many places, buttons and dialogs have been reduced to simple text, sometimes without so much as a box around it. In iOS7, tapping a word is in; visual feedback following that tap is often out. Am I supposed to think that's cool? Edgy? Hip? Maybe it is those things, but one thing I can tell you it's not...useful. Did my tap register? Hmm. Is the app frozen? Hmm. Should I re-tap in a different place or manner? Hmm.
iOS7 has stripped away so many of the visual clues we have grown accustomed to...clues we have become versed in, not just by using touch screen devices from Apple for the past few years, but a visual vocabulary honed in the civilized physical world, over the course of hundreds of years.
The color red means something serious. It has since the dawn of man. A red delete button means business. iOS7 has reduced delete to just a word. A casual word. Delete? No biggie man, go for it. Or not. Your choice. It's cool. Just tap a word!
There's a reason traffic lights aren't just backlit words. There's a reason currency isn't just printed words on white paper. There's a reason UI designers have used fake button press animations since day one.
Up until iOS7, Apple has spoken, and supremely understood, the universal languages of the physical world, and translated them to near perfection in their 2D interfaces. Universal shapes. Universal colors. Visual feedback that confirmed when something could, and denied when it couldn't.
With iOS7, Apple seems to have forgotten what has made Apple Apple; that they understood the physical world better than most anyone, and turned the universal language of the physical world into pure poetry. It's why the iPod was such a hit. It's why the iPhone redefined the mobile phone. It's why every laptop now looks like a MacBook.
iOS7 looks like Android and Windows Metro had sex in a blender, snorted some coke, dropped some acid, lost too much weight, spent all their money on 80s albums, and forgot everything anyone ever knew about user interfaces.
Restoring now.
Dont get me wrong, I do not like anything about android at all, but credit where credit is due. 
