I agree that game should be co-op. Like Resident evil 5, it should let you have another player play the partner. You can always have the second player play catwoman which would be great.
I like this direction of game so far. It kinda goes in the direction of Batman Inc where Catwoman is his partner in comic. Since Robiin is with Dick Grayson now, Catwoman would be a great partner for Bruce in comics as well.