For what it's worth, the other benefit of BB I've valued is the efficient way it deals with mail (without HTML) and renders attachements server side.

On my home network with unlimited data plan it doesn't matter, but when I'm roaming, and I'm paying, it's great.

Roaming with my carrier is 7.50 UKP (~ $15) per megabyte. But I can be away for a week and see a total charge of 5-10 UKP ($10 to $20), receiving and sending all my work and personal mail on the BB whilst I'm away. I just have to be careful not to browse of use apps like Google Maps!

I think when, for example, you read HTML mail or get attachements using a WM device, you're pulling all the graphics/original attachment to your device, which could be rather expensive to say the least...