Hi,
I have recently switched from a Nokia 6310i/Palm T3 combination to a blackberry 7100t, mainly because T-mobile offered it as a free upgrade from my 6310i. I have had it for about a month.
First impressions are:
1. Setup was much easier than the T3/6310 combo, but a lot of the information is held off board so that if you live in an intermittant signal area it can be a pain. You can also set it up so that you can access the settings over the web which is how I eventually got around the issue.
2. I pay £10 month on top of my voice tariff for 'instant email' which gets the push email service. For straight messages this works pretty well, but its handling of attachments is not as good as 'documents to go' on the Palm.
3. The 7100 series is the first bluetooth enabled blackberry and it is a big fat porky pie. The only thing you can connect is a headset. From trawling google I understand that you need firmware version 4.0 to get bluetooth to connect to anything useful like a pc. (To find the version of firmware access Settings, Options, About).
4. It appears to eat power, so you have to be pretty rigourous about charging it. However it does come with a usb charging lead so that you can plug it into any pc to charge.
In summary its an ok phone, but if I had spent money on it I would be a bit disappointed. You might want to see the other PDA thread as I think the future is definitely a dual WiFi / mobile device.
HTH
EG