Fast-paced, intense, unpredictable. The acting is all-around top-notch. Jack Nicholson, Mark Whalberg, Martin Sheen, Matt Damon, Leonardo DiCaprio work tremendously well as partners and adversaries.
Edgy characters find themselves in dicey situations and we have no idea if they would get caught, live or die. The actions are honestly brutal and bloody. The dialogues are crude, but sharp and witty. The web of camouflage entangles everyone in it.
I wasn't too enamored with the ending; it provides a closure but not entirely satisfying. This is one of those films where it could have ended one way yet goes into another direction and then another. Overall, a brilliant masterpiece from a masterful director. Just be forewarned, allow extra time out; it runs for 2.5 hours.