I finally have iOS 11 dev beta 1 installed on my iPhone 7, and thus far, it's stable. I enjoy the look of the new Control panel, but the pull down notification screen displays my lock screen wallpaper. I was at work during the keynote so I'm not sure what's what. In regard to the native Mail app, I like how the mailbox name is enlarged. The redesigned calculator looks awesome, in my opinion. The new look of the App Store is quite nice, as well. I take it that iCloud Drive app is now displayed as the "Files" app? Never mind. I can see the iCloud Drive within the Files app. Anyway, so far so good running iOS 11.