I like the 750, I've had it for about 9 months now and it was my second PDA phone after a older blackberry.
I like the fact that its windows mobile over palm os, as this allows a larger variety of applications to be installed. The only downside is the lack of built-in wifi. I use t-mobiles internet plan and that works at a good speed though. Only big issue i've had is if you get too many things going, ie mail, internet, and then phone-call the phone tends to rapidly slow or lock up.