Fun game if you can gather a like-minded group.
Want to stealth run a bank? You can.
Go louder than that vuvuzela during the world cup's? Sure thing.

Just a few things of note about this game:
+POSITIVE+
+Guns feel nice
+Skills feel meaningful
+Skills not needed anyway if you're good

-NEGATIVE-
-Quickly degrades into a game like L4D or Killing Floor except with cops
-Stealth is frustrating at times
-Grind

All in all still a pretty nice game and certainly worth getting when it's on sale.
Note that of the DLC the only one I recommend really getting is the Gage Mod Courier mod. The rest can be hosted.