I've had all of the iPhones except the 4, although I know it very well as a device mainly because I have family and a lot of friends who have one. I just recently picked up an Atrix.
I agree with you 100% about Android over iOS. My phone is so customized, it's unbelievable. Especially after coming from iOS, it feels like freedom. So, of course you get all of Android's perks when getting the Atrix.
However, the camera (at least imo) SUCKS. Like, really bad. At least in comparison to the iPhone 4's.
The display, eh. The Retina is awesome, no doubt. Can't really hate on it. The Atrix display though imo is quite nice. With brightness maxed out, everything pops really well, especially Mario on my n64 emulator! xD
My only problems are as follows and these are extremely debatable because I think I may have a faulty device:
1) I have had horrific battery life. Completely terrible. I have taken the phone out of the charger and in about 20 minutes, I'm down to 90% without doing ANYTHING. I often have to charge it multiple times a day.
Please though, don't let this scare you away from the phone just because I've heard so many reviewers say the 1930 mAh battery is a beast.
2) The lag. I don't know why, but I experience a considerable amount of lag on my lockscreen and homescreen. I'm using Launcher Pro Plus and it just doesn't appear to work as smooth as it should.
3) Blur. I honestly don't hate it, but I really enjoy LP Plus. Customization is just enhanced that much more.
Great phone overall though, I highly recommend it.