Super impressive. A return mission from the far side is very technically difficult, and pulling it off paves the way for a staffed lunar lander on the far side.
Having to route all of your communications through a relay, having to explicitly build out backups to your backups for comms rather than being able to look up with your instruments, a longer delay requiring more autonomy on the lunar surface, more radiation, more micrometeorite impacts, rougher terrain, other things.