Personally, I don't like the Blackberry UI / OS. I've used several (in testing) and I prefer Pocket PC OS. That is a personal preference but if you like the OS, I hear it is a good unit.
But, they are reliable and built tough and (from people who like BBs). Some friends of mine use the 8830 w/ Sprint and they love it. They say the touch button / track-button wears down after a little while, though.