I must say that I have both. I have an unlocked BB 8700c that I use for my work phone, and an iPhone for my personal phone. Both are great for different things.
The big thing that people will talk about why they love their BB is because of the e-mail. If that is the most important thing to you, I would not recommend the iPhone. If you use it for just about anything else I would recommend the iPhone.
I have had my iPhone since July, and I still don't like the keyboard. It works, and I can type on it somewhat quickly, but I don't like it. The auto correct seems to work pretty well, so that makes up for some of my mistakes, but I do prefer to text/e-mail/blog on my BlackBerry.
So apparently my advice is to have both. How'd I do?
"The lesson as always, I'm an idiot."