Blackberry Pearl v. iPhone?

I am winding down on a long search for a Smartphone and have come to these two choices - Blackberry Pearl or iPhone. I am currently on the Verizon network, so switching to the Pearl would just be a phone upgrade for me (with the renewal of my contract). The downside is that Verizon's charges for unlimited data services are very high (from what I've heard). On the otherhand, I would have to switch to AT&T for the iPhone, which I'm very wary of. I've heard the service plans for iPhone aren't as expensive as what I would be paying for Verizon, but the phone itself is pricey and I hesitate buying into a 1st gen product line. Any advice to help me make my decision?