Its reasonably active. i still get a lot of matches most of the time. not too many high ranks though, *most* of them aren't really legit anyway and some just claim they are good on their bio's but run away at the first sign of impending defeat. check the replay leaderboard, that will give you a better idea in a sense as to who is still playing.
PLEASE NOTE THAT IF I GET A RANDOM FR WITHOUT A MESSAGE, I'll DECLINE IT.