Taken on its own terms, Punisher: War Zone is everything it is supposed to be: excessively violent, larger than life, fast paced, and almost always loads of fun. War Zone doesn't take itself seriously and it doesn't ask the audience to do so, like the '90 and '04 films did. It never ponders the morality of its hero any more than necessary; it's The Punisher for gods' sakes.
The casting of Ray Stevenson as Frank Castle is, in a word, perfect. He is commanding, intimidating, and always fun to watch. If you can't enjoy Stevenson as The Punisher, you shouldn't even be watching the damn movie. Though the film is shot tongue-in-cheek, Stevenson stays consistent but is almost always interesting to watch. The supporting cast, led by Dominic West as Jigsaw, also shines in several scenes. There are no weak links in the cast to undermine WZ the way, say, John Travolta undermined the already-suffering Thomas Jane Punisher movie.
There are many reasons to fault the first two Punisher pics for perhaps giving the character a bad rap, because the critics sure seem to be roasting this more than necessary. One perplexing review comes from Roger Ebert, who seems to praise the film in several ways while outright damning it to the same exact two star rating he applied to the first two (far dumber and less entertaining) Punisher movies: "The Punisher: War Zone is one of the best-made bad movies I've seen. It looks great, it hurtles through its paces and is well-acted. The soundtrack is like elevator music if the elevator were in a death plunge. The special effects are state of the art. Its only flaw is that it's disgusting."