Long story short, this game is old school.
Game-play:
There is not much to say about the game-play except you shoot bad guys with different guns. I find the weapon models to be decent; though if you were into realistic gun models you're better off with R6 3: Raven Shield. I am not a great shooter, so I have a tendency to run out of bullets in-game.
The AI is frustrating. Although enemies alternate between shooting and taking cover, they inevitably charge into your sights once you retreat to a good enough spot; simply rounding a corner would do it. The enemies do use grenades now and then; that provides a bit more action without posing any real threat. I am most impressed (not!) with the AI's uncanny ability to lay traps. It seems the bads guys always find Jack at the right place and the right time. It is intense the first couple of times. Then you find it terribly contrived.
Screenplay:
Almost non-existent. There are some scripted dialogues that you can eavesdrop for a bit of dry humor, but I find that hearing those minions talk makes me want to kill them more, and fast. Some of NOLF's characters make cameos, notably Volkov and Archer (briefly), but their presence is subdued.
Recommendation:
Why not? Although I rate this game poorly, it offers a different flavor than NOLF 1 and 2. If you want to play NOLF Rambo style but can't bring yourself to turn Cate Archer into Lara Croft, then you might find the $7 (w/ shipping) that Contract JACK fetches on Amazon to be acceptable.