Blackberry Bridge keeps me committed
I know Playbook fans are few and far between, but there really is no other tablet that performs like it in terms of being a companion to the phone.
My daily-driver is a beat up old BB Style 9670 I picked up on Ebay, running BBOS6. In short, it is a dinosaur of a phone. I love it, though because it is built like a battleship and has that precious full qwerty keyboard that's seriously like crack cocaine for the thumbs!
I probably would have switched away long ago if not for the added functionality of the Playbook and Blackberry Bridge. Email, contacts, BBM and text messaging can all be handled from the tablet, as well as web surfing and social networks. And I don't have to pay extra for a data plan!
And it just works. If I carry the phone out of range, Bridge automatically picks back up whenever I get back in range - no need to reset anything or fiddle with commands. And for all their talk about "it just works," I can't get my brand new MacBook Air to remember my home wifi connection - even if the computer simply goes into sleep mode!
I don't know if RIM can still compete now that the tablet market has really heated up, but I find it interesting that each of the new "big dog" tablets have incorporated Playbook-style gestures in their UI's. And to date noone else has even come close to the symbiosis of the tablet and phone that RIM has achieved.