I'll take a stab...I implemented a BlackBerry solution after checking out the PPc solution.
*Self-contained. Vertical system, running on a separate server, that the MS platform neither knows or cares about. PPC requires either a) Exchange Server 2003, or b) GOODLink by GOOD Technologies.
* Secure. BB is triple-DES encrypted. Gov't has been using it for years.
* Trusted, tried and true. BBs have been out there (1MM of them, per RIM) for around 10 years.
* Vertical system. Double-edged sword; if you don't know what you're doing, you're in trouble (or VERRRY dependent on RIM).
* Support = $$$$. EXPENSIVE support.
* Like a pig with lipstick on. The 7230 is NOT pretty. However, the 7100t is REAL nice lookin' (check http://www.getmoreblackberry.com/)
* Clumsy device. Talking into the phone of this thing is like using a knife to eat soup (it'll work but it's very clumsy).
And no, I don't work for either TMobile or BlackBerry.