Thoughts so far.
New messages is way better looking. Didnt ever like the old chat bubbles much.
The parallax effect is very subtle, but very cool. Nice touch.
A few of these animations are a bit slow. Not as in laggy, but as in I have a feeling in a few days the "COOL" will wear off, and the half second it takes will begin to get frustrating.
Its about damn time for expandable folders and an easy to access flashlight. Next needs to be an option to click and hold to access wifi settings, DND settings, etc. But overall, a good step in the right direction.
New notification center is good looking too, and less cluttered feeling than the old one.
I look forward to more apps updating their interfaces to match iOS7, its a rough transition in a few apps going from the crisp cleanliness of the os, to oldschool looking apps.
I also hope Mavericks makes some UI overhauls that match iOS, I already know they are ditching a bunch of the terrible fake textures (I'm looking at you calendar, with your fake torn pages and cork texture), but I would love if iChat looked like messages, etc.