While very clearly a knock off of Spyhunter, this is still a legitimately fun game.
I. Love. Spy Hunter. I bought the NES game at Value Village and played it for four hours straight that day. I'm still not any good at it, but boy is it fun. Surprisingly, this game is actually even more fun because of it's a far more varied experience. Each of the five levels includes a land portion and a flying portion (the helicopter bits of spy hunter were scrapped due to memory constraints). Sometimes the land parts actually take place in water which isn't that different, but mixes things up a bit.
On a more specific level, there are many things which make this game more fun than Spy Hunter. For one thing you start in a motorcycle but can collect little letters to get a car which protects you considerably. This gives you a good goal beyond surviving. Furthermore, the game includes several codes which ease the incredible difficulty (it is about as difficult as Spy Hunter). Of course, even with the best cheats, I only got past the second level the first time I played. Another nice benefit are the graphics, which are much nicer and less repetitive than Spy Hunter on the NES (which is to be expected from a SMS game of course).
Of course, this game has some problems, as do most games. The music sucks (though the sound is good) and no one can ever forget the Spy Hunter music. The game is also still crazy hard, and since it isn't an arcade port I would think they could get away with toning it down a bit. The biggest problem is, however, one which plagues all Master System titles: that stupid controller. The pad is way too sensitive, which leads to some problems with walls when speeding up and slowing down the car. This is not such a big deal when sliding left and right though and your car maintains speed without holding up.
Overall Action Fighter is a case of the imitator being better than the source material, largely due to the Master System's more powerful hardware. It does lose marks for terrible music, sensitive controls and overall lack of originality. But don't let Action Fighter fool you, it's worthy of your collection.