I find it to be solid, rather than bulky and heavy. Very reassuring and lets me know it's there.
The Notifications are simply awesome. I love it!
The autocomplete as you type is worth its weight in gold... the more you type, the more predictive it gets.
Speed is the key! And this thing is lightning fast!
I do not like the app market layout, there should be an exhaustive website out there on which to shop, note worthwhile apps and then order from the phone.
Multiple browser windows can be a bit tricky and I have to remember to close some when I'm done with them. Not a complaint, just a note to self.
All in all, well worth the upgrade. I think it will be awhile before another phone comes along to woo us away from the Droid!