Great story line. The execute feature makes the game fun to play, but as of now the multiplayer side seems nearly dead.!
However, there seems to be no real challenge to it. There is no hiding the body as their was in the last ones, and whilst engaged in a firefight in one area, the guards in the next area are completely oblivious that a firefight was taking place, the downside to lacking a proper alarm or alert system or not making it so baddies in nearby areas will be on a higher alert status. Kinda makes it too easy. Interrogation is a bit wacky too. There seems to be no resistance in the guards you interrogate, even the tougher ones. Sure, some might break at the moment of getting bloodied up, but some of them, I think should make it hard to obtain info and not given within a single bash-in with a sink or toilet. The other side I don't like about the interrogation part is the fact that you don't have a choice with what to do with him. Before you could choose between knocking him out or killing him by a fatal blow, or my favorite way of doing it, shoving him off the side of the building. Interrogate, maim, and hide the body at the same time.
However, I guess in the end it doesn't really matter how it is done. The result will always be the same (except in Double Agent of course). Kinda sucks they went with killing Lambert off, considering when I played Double Agent I didn't go through with killing him since he was one of my favorite characters.