I've had a Blackberry Bold and currently have an iPhone. The iPhone is a much better gadget than the Blackberry but a much poorer phone – so it's really down to priorities.
I prefered having a proper keyboard and find the poor reception on the iPhone a struggle (I keep an old Nokia E51 in my laptop bag to use in poor reception areas) so overall I preferred the Blackberry.
We're finding the failure rate on the iPhones is a bit higher than we had on the Blackberries, although not to the point where it's been a serious issue.
My wife decided to get a 64Gb iTouch and a proper phone instead of an iPhone when she had the choice recently.