I had Battle report of by default since the messages didn't tell me anything usefull. But now with the Rating system implemented it might be insightful to get those end of game reports, to get a better feeling for the rating system.
Because of this I flipped it on at Settings. But after a challenge of mine was accepted, I was reminded that mesages that state the obvious about a starting game existed too. These are still completely useless.
So, I suggest making it possible to set up that you do want Battle reports, but don't want System messages (as I call them for now).