I bought it some months ago and played it often with 3 of my friends (you really should have a full team because the AI of the player characters is very cheap).
It reminds a lot of Left 4 dead but in a police/heist scenario with the difference that your enemies have guns and a ridiculusly good aim. So most of the time you're camping on corners mowing down waves of seemingly infinite number of police officers/swat teams etc. and waiting that your next target fulfills (often targets are unlocked through waiting a given ammount of time (waiting a automatic saw to open up a tresor etc). If you are able to breath again you move on and search for the next corner to camp hoping you got far enough so your ammunition won't run out.
I really won't say that it is a bad game, since it isn't, but the really hard enemy aim and the long playtime of some scenarios are sometimes demotivating, while you have several skill trees you can level up and unlock special items you can use.
Get it for <5$ and you'll make no mistake but be sure you have at least 3 friends to play with, else you won't have that much fun with Payday.
