My firm deals in Nextel and AT&T Wireless, both of whom offer Blackberry phones.
That's not my field, but my take is that volume is low in these products and the main adopters are businesses who are using them for some kind of custom app or as part of their order infrastructure.
The devices still seem a little crude and unwieldy for every day consumer use. One of our people did an eval for a week or so, but checking e-mail was tedious. Instant Message ability was cool, but there was no compelling business reason to adopt this technology. The monochrome, low-res screen isn't too appealing, either. On the plus side, the unit was not heavy or bulky - a breeze to carry around, even if it is a bit wider than some devices.
Overall, I think the cell phone/PDA combo is the form factor business people will adopt. (I currently carry a Nextel and a CLIE, and would be delighted to combine the two.) I think it will look more like a PDA that you can talk into than a phone that does PDA stuff, since screen size and resolution will drive this, IMO. Postage-stamp size screens just aren't very good for serious use.
My guess is that Blackberry should focus on the early-adopter business markets, much in the way Nextel has done with its radio feature. Consumers seem to be more interested in color screens and camera features in their high-end phones.