We have a bunch of blackberries here at work, from multiple providers.
Doesn't really matter what provider it's from the functionality is basically the same (even if the form factor is a little different).
Grab a blackberry & play with it, see if you like it.
Alternatively, grab the development kits from RIM & simulate one on your own PC - It will do everything the real thing will do (full simulated OS & environment).
Viper GTS