Unfortunately Ghosts are only between 2500 - 3500 People Online (WORLDWIDE !!) to various "peak hours".
Ongoing care, the waiting times in lobbies. Many a game mode, you can completely forget there are simply too few players online. Only Team Deathmatch (normally not hardcore) goes halfway.
Due to the small number of players you have to give with the opponent satisfied online (mostly American kiddies) .. shame really because I would find the multiplayer part ansich not so bad ...
Single player I've not played on the ONE because as I said already knew of the PS3 ..