I imaged iOS7 onto my iPhone 5 (UK) last night.
1Password: I could open, sync and browse the data fine. But I couldn't copy anything to my clipboard, in order to paste into another app.
The Economist: Opens but then soon dies as it tries to sync. Dodgy bordering, and wouldn't load the magazine.
FT: This is an HTML5 app which somehow blacked out the indicator bar (clock, battery, signal). Could barely browse articles.
Day One: Opened, synced and works perfectly. Only thing worth mentioning is that the search bar looks very out of place... you'll know when you see.
Downcast: Seemed to work.
Other than that, everything seemed OK. I noticed some rather jittery transitioning, smooth settings screen, unexpected apps closing, the occasional reboot and quite a few black screens. Initial impressions of the battery were OK. Didn't seem much different. In fact, the biggest annoyance was downloading applications at the start - I couldn't cancel the download.
Overall: Loving the new look, works great. The Beta 1 is certainly miles ahead of other Betas I've tested, but not enough for my main mobile phone. Looks like I'll need to invest in a secondary.