I used a Treo for years and recently changed to a BB 8830. I have been on a BB forum a fair bit voicing my frustration... Here's my conclusions..
A BB does email way better. (And cheaper due to compression I suppose). You can use multiple email accounts (work/hobby)Attachments are managed better. Security is better, but somewhat less friendly. For example, I can't mark specific contacts/appointments private (also handy in this hobby) like I could on the Treo. It's kinda all or nothing....
The BB is not as good at easily setting appointments. (I liked the simple Palm desktop. Outlook is cumbersome for my needs...) The BB has some odd problems... like ringer volumes etc. It is an incredibly complex, sophisticated gizmo... but it is not primarily a PDA, nor a phone. It's an email thingy...
I find this forum useful, and wish I had found it before I bought the BB.
http://www.blackberryforums.com/ There are sections to do with specific models. Many of the mods are serious Crackaholics so bear that in mind when you read their answers.
Do I regret my decision to change? Well, I guess not as I still have my Treo and could easily switch back. If email is your primary need, do it... The BB works very differently and I found it helpful to stop comparing the two units. It was just a case of adapting to the new, but not always better, way of doing things.
EDIT: There are difference in capabilities depending on whether you are configured to use the BB on the Blackberry Enterprise Server (BES) or Blackberry Internet Server (BIS). I assume that you are the latter... the BES is for the corporate types...