I don't know that I'd call the coop quick. Some of the missions can take a while and some of them can be frustrating as you try to figure out how to get through it without

ing up too badly. If you get wiped you go back to a checkpoint, and that does happen. I also think only some of them have a 4 person requirement.
Lastly, if you're going for the plat there are collectibles in the coop maps and they can be pretty hard to get to solo, so have a map handy as I don't think they show up until you walk near them.
Edit - it also helps immensely to have better gear. When the shit hits the fan they throw a ton of guys at you with a mix of ranged and melee from several directions. Without better armor they'll kill you quick.