Well, it gave me quite a bit of field experience that required me to work closely with the Malnosso for an extended period of time. I also encountered a number of hostiles called "cultists", and performed reconnaissance. As Yondaime-sama personally relieved me of duty, I delivered my mission findings to him.

[ In other words, sir, you'll have to wait until Minato returns to really find out what Kakashi discovered because Kakashi isn't even entirely sure how much information Minato wants shared. ]