I'd highly suggest going here first:
BlackBerry FAQ - BlackBerryFAQ
especially the part titled "Why Blackberry?" It really has helped me (and I'm sure a lot of other folks) who were at first curious as to what the BB revolution was all about. Many years later, I've been (and likely will always continue to be) a Blackberry fan, user, and amateur tech support for all the friends I've turned on to a BB (including my wife)