New signal strength icon (circles) is a bad and amateur design choice (just like the most of the UI). The way it looks now it looks a lot like a password field with hidden text. And to get the idea about signal strength you need to count circles while previously you just looked at the last bar and immediately get it based on its size.
New icons are cheap, amateur and there's no any reason and any sense to make them flat, especially when you add new 3D effects such as moving wallpapers and Safari 'stacks'.
New quick settings aka 'control center' panel is a total mess. If it's done it should be done way better.
App switch panel is a step back now you see only 3 icons at a time instead of 4, and app previews are only distracting. It's way easier and faster to navigate by icons.
Removing buttons and visual highlights and replacing them with plain text is a one more step back and a nod (why??) to Android and Windows design. You need to spend time trying to find a button and guess if it's a button at all.
^That's why Siri panel now shows "Tap to edit" under your question, since there's no any other visual clue that it's tappable. When you have to explain something (what was clear in iOS 6) to the user it's a very bad UI design.
Share panel is a mix of colored and outline icons. Again you need to make an effort to differentiate between outline icons, they're harder to read than before.
The whole UI doesn't feel consistent, you always need to guess something or spend some time in an app to just understand the interface layout. Getting tired and bored very quick.
iOS lost its unique, rich style. Definitely a huge step back.
I agree with a lot of your points. Similar to with what The Verge said:
http://www.theverge.com/apple/2013/6/10/4416726/the-design-of-ios-7-simply-confusing
Personally, I find the UI "too flat" in a lot of areas, especially the buttons. The lack of depth makes it harder to distinguish certain aspects of the UI and I'm still stumbling with it a bit since yesterday afternoon. I think a good example is comparing the new Mail app to the iOS Gmail app. I used to think the Gmail app was too flat but it pales in comparison to the stock apps (Messages, Photos, Calender etc...).
Perhaps, I'll get used to it. The muscle memory hasn't developed for the icons and such. I do hope however, that Apple continues to add visual tweaks and consistency throughout ios 7. Even for a Beta 1, it seems a bit unpolished for Apple.
As for the icons, I'm not impressed by them but at the same time I don't hate them. I have been using winterboard themes since ios 3.x so the change isn't to drastic compared to some of the themes I've used. I like what
downpour did with his/her mockup. This is what I expected when Apple said "flat". It's not as vibrant I supposed, but apple's icons just remind me of a blend of MIUI rom for Android and the Nokia N9.
BTW, I like the control center. The layout isn't perfect but close to what I had on my jailbroken phone with intelliscreenX and NC settings. But I guess that's just personal preference.
Notification center looks nicer but no major functional changes. Actionable notifications are past due.
App switching is a downgrade in functionality (4 to 3 icons) but looks nice visually. There have been card switchers in the jailbreak scene for a long time now and I never preferred them over simple list or icon switchers which are more efficient.
Overall, I'm left with the feeling that many of the changes are to combat critics that have dubbed iOS outdated and boring rather then innovation. Perhaps too much focus on UI changes, bright colors and flattening everything out. Beta 1, maybe they will prove me wrong.