In the first few weeks that Madden was out, Co-Op was NICE... Most all of the people looking for games were aware of their responsibilities. It was the closest thing to real football I'd experienced in a Madden game because of the sense of teamwork and the disappointment when someone fails (namely myself).
Online Co-op is easily the best addition to the game since defensive playmaker... BUT you really find out who knows football and who doesn't. Most people don't.
After about a week and a half of co-op games, the players you don't want on your team caught wind of it and it was almost impossible to find players that knew how to play their positions. Folks started quitting midway thru games, etc....
Where cheesy arcade play fouls the online experience, unskilled players kill the co-op experience. If every Madden player were skilled in the basics, Co-op would be FANTASTIC. But there were so many unskilled players, I stopped playing co-op.
That said, I'd play it again in a heartbeat if I could find a decent team...
Later