I use BB and there is no Blackberry/iPhone etc mobile app for it (people frequently request one on their forums).
I really think data entry wise BB and GWF are very close and GWF is a little less $ (and you can set what intensity to count -METs), not sure about their reports or whatever though.
I really like my BB but would get a GWF if I were looking to purchase such a device.
I bet others will give you some more detailed info.
Began this quest on Sept 2,2008...
***These are the good old days!***