I was a bit curious (patch 1.2) and tried it.
You know what happened?
My own Achievements have been replaced by the achievements of the person I looked at.
Do NOT compare your stats.
All I can say is - **** you UBISOFT and give me my achievements back.
I couldn't get all of them the first time because you're too dumb to code them properly.
Edit: Relogging doesn't change anything.
I was hoping that this is just a display bug but it is permanent.
Please stop making games and retrain into cleaners.
You can clean up your mess faster this way.