I was shocked to see a movie with a writer actually playing one of his characters, especially one as iconic--or, at least, notable--as Mike Hammer. I can only recall Stephen King playing in some of his scripts, but even then he did not tend to be a major, featured character. His stories have soared most with great actors, writing, and directing behind them ("The Green Mile," "Shawshank Redemption," "The Shining," "Misery," and many others).
Mickey Spillane is woefully short of King's humility, though. The movie has an intriguing plot, but is convoluted beneath the weight of bad acting and mostly wretched delivery. The dialogue is actually pretty believable, all things considered, but you can feel the crowd assembled on the screen is mostly amateurs. The amateurish feel coupled with the somewhat on-target dialog sort of coupled to create a more "fun" movie than what is probably intended and it stays thin on the noir-ish elements, which often seem clichéd in most movies anyway.
Spillane is generally horrible as a supposed slick lady's man--which Stacy Keach carried off much more believably with his charisma and acting chops, if not looks, on television. Spillane's pretty dry and one-note as Hammer, but at least he doesn't tend to ham it up. In fact, I'm not sure he is capable of ham.
Shirley Eaton is excellent as the eye candy and Hammer's love interest, but Spillane just butchers some of his lines with her; for example, when she asks Hammer if he loves her, Spillane lowly rasps in the back of his throat, "I think I do, baby." It's really a pretty lame attempt at being emotional. And, kissing together? Just horrible face-mashing and a real waste of such an exquisite beauty as Eaton's. Spillane just has no idea how to be expressive and believable; his face is just a pancake throughout the movie. It gives a certain "naturalism" to the movie, but probably not in a good way for someone that needs to be as dynamic as Mike Hammer.
Though it would have been very easy to have it, there is almost no dramatic tension in this movie, just a series of pasted-together scenes that Spillane meanders through. On a highly superficial level it works--the basic pieces ultimately fit--but there's no elegance to the design, probably due to lack of presentation on the part of most of the actors.
The story is good enough to be re-made as a true noir-ish exploit, but the acting and stylistic elements need a real working through.