With the “iMminent” release of that little device from Apple, the debate has already begun as to which is preferable: a touchscreen with a virtual keyboard or a true keyboard. To me the question misses the main point, which is to ask yourself why you have a mobile smart phone in the first place. It isn’t that one is “better” than another; it is that each interface has its advantages depending on your intended purpose.
For those who need to type a lot of text, the true keyboard is most likely the superior choice. (I say “most likely” in that I have not yet tested the virtual keypad on the iPhone, and so cannot definitively give an opinion as to which I find easier to use.) So if you are like most BlackBerry users the mechanical keyboard will make the most sense.
However, there is one advantage to a virtual keyboard: it allows for a larger screen. The larger screen in turn offers all sorts of advantages, especially when it comes to viewing pictures, movies, or web pages. A virtual keyboard is a tradeoff one makes for a larger screen. (Although even this might not be universally true, in light of a recent patent. -ed)
So ultimately there is really no clear winner in this debate. Like with most options in life, there are tradeoffs and it is up to each individual user to decide what combination of features best meets his or her needs. The winner is the consumer, who has both the blessing and the burden of being offered a choice.