I tried to play it just now, but the damn matchmaking system for it is imo inexcusable and lazy. They expect me to wait 25 minutes just to get access to it? No, no way Valve! Either give this mode the same quick search function that the multi-player has, or just get rid of co-op mode altogether.
Also, tried searching servers through the servers menu, and everyone I've found with this mode is password protected, so no luck there at all.