The Motorola Atrix 4G has the familiar Android interface along with their proprietary MotoBLUR additions. Similar to the recently released Motorola Cliq 2, and Motorola Droid Pro, this version of MotoBLUR is actually much less intrusive. As it is a touchscreen interface, it's very easy to learn and pick up for new users, and for older users there's very little need to get used to the interface. The response time is faster thanks to the dual core processors.
The biggest difference that the Motorola Atrix 4G brings is the fact that it can practically change into a Linux powered laptop that can run Flash and Firefox. The laptop dock literally changes the smartphone into a laptop that can be used just like a regular computer. It boots up extremely fast and adds another layer of usability. Also, while using the computer, the dock actually charges the Atrix 4G, meaning that once you're finished with your session, you're not left with a dead smartphone.
The HD dock is also another amazing addition to usability. Simply use the HD dock to connect the Motorola Atrix 4G to an HD device. The interface loads to a different screen, allowing you to play music, view files and use the Atrix 4G on your HD device, such as an HD monitor or HDTV.
Overall the user interface on the Motorola Atrix 4G, is an amazing experience and really takes smartphones to a whole new level of usability.