I was a long time Blackberry user Pearl and then 8530 - now with Droid X. Overall, I'm blown away with this phone. Although I find myself fiddling with it way too much.
Currently the X does not cut and paste in all instances. I think the 2.2 is supposed to resolve the issue. That was my biggest gripe.
Calendar and email sync has been really simple. I did like the stock BB calendar better than the X. But the pure calendar widget helped visually. You can make calendar entries while talking. Plus, my calendar "location" entries from outlook on desktop syncs with google calendar and map location info is linked with directions, reviews, etc. on the phone. I couldn't believe this the first time I realized it.
I though I would miss the trackballball, and I did for the first week or two. Now I can't even remember why. And now that I'm getting used to Swype, I don't really miss the physical keyboard.
I do have minor complaints about the phone, but most can be fixed with an app. And as I said above, I'm blown away. It's like going from a Razor (great phone in its time) to the Blackberry x 10.