I got a Blackberry Curve for work - and have been using it for about 3 weeks. As a smartphone it is horrible - screen is small, navigation within the screen is horrid, and in general doesn't have much going for it. And the famed keyboard - I find it too small, and tend to make a lot more mistakes than with my iPhone while typing.
But it's not all bad - the battery life is amazing; it is quite responsive, and the enterprise integration for email and contacts work very well; and viewing office documents is easy. That doesn't mean that the iPhone doesn't do these things well (except for the battery life); but the Blackberry does show what focused purpose devices can do.
Regardless, I am not giving up my iPhone - maybe the Z10 would have changed my mind - the iPhone remains the superior platform.