I went from the Droid X to the iPhone 4 and now the Bionic. LOL. It's been quite a while since I had the Droid X, but the Bionic so far is a much more satisfying phone.
They both have very good build quality. I thought I would not like the capacitive buttons as well, but I actually prefer them and they look nice. The overall design of the Bionic is nicer, IMO. I do not mind the Pentile screen at all, though the iPhone 4's screen is still considerably better (but smaller).
As for Motoblur, I could care less because the first thing I installed on both phones was Launcher Pro. I can say, without hesitation, that the Bionic is much smoother with less hitches than the Droid X ever was. The Bionic doesn't lag at all, except maybe the camera interface which is still not great (the X's was not good either, IMO).
Of course, the highlight of the Bionic is LTE. It just got turned on in my area this morning, actually, and I'm getting anywhere from 5-20 mbps down, and 3-5 mbps up (depending on my signal strength). On average, I'm getting about 10 down and 4 up, which I think it quite excellent and beats out the average broadband Internet speed in the USA!
I'd say the Droid Bionic is a worthy upgrade to the Droid X. My only gripe, really, about the Bionic is battery life - which is NOT good at all, especially if you use the phone mainly in areas with lower signal strength. I'm using the extended battery and barely get 10 hours of battery life (with the phone in my pocket 75% of the time). The Cell Standby just using up juice like it's Koolaid! But that's the tradeoff you get for LTE right now. And that's why Apple isn't going to do an LTE iPhone this year. They are probably smart for waiting, but for those of us who like to live on the edge, this is all gravy! I will probably switch back to iPhone when there's an LTE version, but that's a LONG ways off...