I've been using Treo's with Palm OS for many years and moved to BlackBerry because my company switched over.
I do think there are many positive things about the Curve, but I just can't get used to not having the touch screen interface that seemed to be so seemless with the full qwerty keyboard.
Can all the ex-Treo users post if they are happy with switching over to BB?
Yes, no, or mixed.
I'm mixed still after a month.