[quote name='pram12']The co-op story ones are really hard (on Hard lol). I wonder what's it like on Crushing....[/QUOTE]
On Crushing it is really unique, all the enemies have skeleton skulls for their heads (for intimidation purposes). The mode also throws "advanced enemies" at you in great swarms early. So expect a lot of the armored soldiers carrying FALs/SPAS, snipers, launch men (GL), and RPG enemies. Of course during the sections where you fight against the Mini-gunners, there is often more of them as well. It is difficulty, but I've done it many times with my friend for the two medals "Back to Back" and "Masters of the Universe" medals.
Also avoid the Plunder coop unless your lucky enough to get a few people who will actually go for the treasure. Otherwise, they just play the mode like it was survival.