The problem with the AI in X-COM 2012, besides the obvious "we got a free turn, problem?", was that it had this weird ass leash, where only like 5 units at a time would actually do anything on a given map. So you did this constant routine of SLOOOOOOOOOOWLY going forward and waiting for the AI to finally see you, after which you started a small battle with usually no more than 5-6 dudes, only to repeat the process afterwards. A mod supposedly fixed it, but I really didn't want to install it, since I am always paranoid about mods like that completely breaking the game.