PC Pro has a BlackBerry Storm 2 review. I tried my brother-in-law's BB Storm 1 and was not impressed at all. It sounds like some of the issues have been resolved, but we'll see how that goes as more reviews come out.
Right now, and please don't take this as me being a Mac/iPhone fanboy, the iPhone is going to be hard to catch, as the thing that is best about the iPhone is the feel of it. I've played with the Pre, the Android, and the Storm, and none match the smoothness and feel of some of the simple operations like scrolling and panning that the iPhone has got perfectly, and have since version 1.
This is probably why it survived it's original incarnation with no 3G, no apps, no cut and paste, and all the other detractors. If the UI is smooth and scrolling and flipping through options feels like it should, it's really hard to use another phone where the scrolling or moving of your fingers on the screen feel slightly laggy or "off". Also the ecosystem built up around the iPhone with the app store makes it a force to be reckoned with.
That said, the Blackberry is firmly entrenched in the business world, and that is something that the iPhone will have trouble making inroads with, though I'm seeing more and more business people carrying iPhones walking around.