I thought 3.0 seemed pretty smooth at first but the more I use it, it is getting pretty bad.
-majorly slow often
-tons of lag in several apps and typing
-crashing Messages app, lots of crashing in new Voice app and weird bugs
-MMS doesn't even work sending or receiving
-Really slow start up and shut down
-Really slow backup in iTunes
-Spotlight is very slow, it is NOT like on the Mac like some people are saying, NOT AT ALL, on the Mac is instant
-My home screen started showing as the voice app screen... WEIRD!
-Can't pan images when pinched in
-Texts dont make that WOOP iChat sound anymore when you send... I dunno if that is a bug, but I don't like not having that
That's about it, but it is far from ready or it will be another nightmare like the 3G release again

I want it SOLID like the original iPhone release!!!
I love it though as far as features etc. I wish for a couple little things like custom text ringtones etc. But can't complain, this is a really big update.
Like I have been saying, after Apple took care of the enterprise features, they returned focus to the users. I think the new iPhone in June will do video with hardware enhancements and Snow Leopard goodness for sure... That is my prediction!
P.S. Anybody else have confirmation from AT&T about MMS already being part of the text plan and no extra charge??? I called them and even had the girl verify with a manager and she said it is all included already, but I have read twice now online that Apple said additional fees may apply. Are they just meaning in other countries maybe???