Our whole office is on iPhones. Blackberry was great three years ago but the 3GS and 4 have blown the blackberrys out of the water. The only exception is the Tour, which was a perfect world phone. The big problem was that it didn't work in Korea or Japan.

I still use my blackberry for international travel because of the ease of switching SIMs, but otherwise, iPhones are no less viable for business.