After 4 Treo's in 18 months and countless soft/hard resets in between, I have become the proud owner of an 8830 from Verizon. Been playing with it for about a week - with much assistance from the posts on BlackBerry Forums.
I'm a lawyer and really need real time synchronization with Microsoft Outlook. WirelessSync did that, sort of, but the desktop application is not terribly stable AND it won't run on a server. I figured RIM had been doing this for long enough to have a fairly polished product at this point AND they had a version of BES I could have for FREE. I'm very fond of the word "free" so I made the switch to BB primarily because of the good things I had heard about BES.
Setting up BES on my server at work was a bit of a PITA, but now it's running like a champ and beats the CRAP out of WirelessSync - AND I don't have to leave a workstation running 24/7 to get calendar info and email.
As additional "surprise" bonuses, it syncs up MUCH better with my car, is about a third the weight of a Treo (at least that's what it feels like) and has close to twice the battery life.
Favorite apps so far (aside from the Outlook integration): BBWeather and Beyond411
If Verizon enables GPS on this device (or if someone comes up with a hack) it will be the perfect business device.