Kowing RIM devices...
I can tell you that the playbook is quite ok when it comes to security. (although it will get rooted sooner than later, although that will only happen if it becomes popular)
However RIM's problem is that they have lost the plot.
1) The current Os 6.0 is a bloody train-wreck, it has so many bugs, that there are bugs on the bugs themselves, the browser is useless, the mp3 player lacks basic functionality (like allowing for making file scan exclusions), the interface sucks on Os6.0 big time, it doesn't fit well on the keyboard models, and lacks on the tactile ones too. It is quite convoluted, the music player for example has many screens depending if you are looking for something or playing something already. You never get the one you want.
2) It is quite likely that Rim will not produce any more "serious" updates to the current bold/torch leaving their faithful and loyal user base with a handset locked to a 1.5-2 year contract. The current models were obsoletes upon launch.
Rim has lost me as a customer. Hello Android (there are plenty of androids bbry-like coming soon)