Done the Sony Ericsson, great phone, but I needed something easier to use for biz.
Picked up the Blackberry curve last year. It is the best cell phone I've had. I use my phone primarily for biz. It is very intuitive. The controls are where you expect them. The camera is better than my digital one. It synchronizes itself with (Outlook on) my laptop with no problem. The issue with the emails is interesting. I just noticed that last week, I thought it deleted the same messages as the ones I've deleted on my laptop. I'll have to start saving important ones until I figure that out.
The key pad is the reason I changed over from the Sony, this one is much easier to use and you can customize all the buttons on the phone for different functions.
The only real problem I have is downloading music, which is more annoying than important.
A good overall phone, I would recommend it.