My girlfriend just switched to a curve yesterday (She is on verizon) from a treo 800w. Her treo would infuriate her from time to time but overall she was okay with it.. Her Curve is like a love affair, she absolutely, completely, loves it. She would have loved to have gotten the curve and told me she hated it (all in fun of course, but she would rather be right than have a better phone) and she hasn't complained except for the fact that it will vibrate, then ring, but wont vibrate and ring at the same time. (There is a cheap program to change that which I will probably end up getting her..)
She has said:
The curve is easier to type on
It runs a lot faster
It doesn't freeze up (It is new, so that's a little biased but still.. her treo froze all the time right from the beginning)
the internet browser is a little different but she likes it so far
Hope that helped.
The addiction Started with a Pearl...
Now I have a Curve 8320 in Titanium for T-Mobile