I have a BlackBerry 9630 'Tour' for my "smartphone" and it is almost impossible to get out a proper gramatically correct email. The keys are too small & close together, and there is no backspace...It only back-deletes, so you can't skip over letters to get to what you want to correct. Capitalizing adds another keystroke to the word.
In a year and a half of owning it, I've only sent emails to myself. Mostly URLs to click with my browser so I don't have to spell it out...