As expected, the teardown reveals a device that's extremely well-designed, but also difficult to repair. First, the retina display LCD is firmly attached to the display assembly. iFixit says you if you have any LCD problems, you will likely have to replace the whole display assembly which includes the iSight Camera, WiFi antennas, and Bluetooth antennas.
The repair company also confirmed that the RAM is soldered to the logic board and is not upgradeable. The SSD is also proprietary and not upgradeable at this point (though, it might be in the future since it is a separate daughter card).
Lastly, the battery is glued to the case and is very difficult to remove. It covers the trackpad cable which may be sheared when you pry the battery out of its slot. Overall, the retina MacBook Pro was given a 1 out of 10 on the repairability scale which means you should proceed very cautiously or leave the job for the experts.