Same story here as the OP...former BB user turned iTouch turned iPhone user. I'm actually registered on TreoCentral, PreCentral, WMExperts, and Crackberry - yes I've used them all (except the pre). I'm one of those people who swore up and down I'd never get an iPhone. Then a co-worker started using a new 3rd Gen touch, and I got to actually play with one and give it a fair shake. Got my own iTouch 32g, and now 2 weeks later I got myself a 3GS 16g (couldn't stand having to rely on wifi all the time; here in the nw subs of Chi it's not always available).
So now we'll see if my wife makes the jump; I'm going to let her spend some time with the iTouch.
What made me make the jump? Not so much that I hated the BB; really enjoyed it in fact. But got tired of the 3-hour reboots, and once I played with an iTouch the web browsing made me throw up in my mouth a little bit. My biggest thing for using a BB was email, but since I predominately use GMail, the iPhone/Touch is just as fast. And I just absolutely love being able to download a free app for anything I need. I bought Docs to Go prem, and can sync my google docs and office docs; just absolutely great. But why am I telling you guys? It's like preaching to the choir!