Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A293 Safari/6531.22.7)
I like it, overall.
The Bad:
The upgrade was sloooooooooow. Had to re-enable sync with yahoo to get my contacts back. OS 3X was slow on mine already, 4.0 is slightly better. No multitasking or background wallpaper.
The Goods:
Folders are cool, Unified Inbox is sweeet. Notes syncs via the web with gmail, ymail, etc. I haven't used it yet.
GEOTAG photos! (it's retroactive too, very cool) 5X digital zoom is interesting, I suppose. Podcast links lead out of iPod, and playlist creation & editing finally.
Calendars also support birthdays (via your contacts).
Overall, not too shabby. Can't wait for iPhone 4, but this will give me something to do for a bit.