For me, having the BB has kept me connected in circumstances when I would otherwise have no ability to be in touch with my office and clients, and there were no other options like a laptop, etc. My EDGE connection is superbly fast. But, no, it is not as fast as a highspeed wireless broadband I might get on a laptop, but then again, I also can't get up from using a laptop and pop it into my belt holster and neither can I be driving down the interstate and grab my laptop to check an incoming e-mail and respond timely.
In my opinion, Blackberry's don't replace the need for a full-blown laptop or desktop. Anyone who thinks it is, will be disappointed--just like you can't use a VW bug to pull a 4 ton load of pulpwood, its just not made for that.
Chang, you need to decide what you want, your purpose, first. Then determine what is needed to achieve that purpose. It might not be a hand-held unit.