Robert Rodriguez’s past films have been weak on plot and heavy on technical glitz. If you don’t believe me, go watch the “Spy Kids” movies again. Even his latest flick, “Once Upon a Time in Mexico” seemed to be more about testing the limits of a digital video camera than actually telling a good story.

But while “Sin City” is loaded with effects, it’s got some really solid writing, courtesy of comic book guru Frank Miller. While I’ve never read the “Sin City” comic books, I have had the pleasure of reading other works by Frank Miller, particularly the infamous “Dark Knight Returns.” He’s right up there with Alan Moore as one of the premiere twisted minds of modern comics.

Which leads me to a public service announcement: Leave the kids at home for this one. Frank Miller was never one to write “nice” comics like Richie Rich - unless Richie Rich had a festering heroine addiction, packed heat and spent his allowance on street hookers.

Make no mistake. This film is ultra-violent. It’s bloody, even if the blood isn’t always red. It’s got decapitations, cannibalism, mutilation, murder, perversion and sexual predators getting their cajones blown off with a pistol. I loved it.

If you’ve read anything leading up to this film, you’ll know it’s one of the first films in which the cast was shot entirely against a green screen. The sets - all created digitally- were later added by a computer. This isn’t the first release to have done this, mind you. Last year’s “Sky Captain and the World of Tomorrow” made a big splash with critics (but a splat with the viewers) using this technique.

However, “Sin City” is a far superior film. The first reason is because of the writing. Sin City is the nickname for Basin City, a fictional town where the good guys are bad and the bad guys are worse. It harkens back to the old hard boiled detective stories. It’s like film noir on crack.

The film tells several interconnected short stories based on Miller’s comic book series. But unlike most comic book films, “Sin City” adheres extremely well to the original material. In fact, it is so close to the books that Rodriguez gives Miller a co-directing credit and based many of the storyboards on the original comic panels. At last, we have a comic book movie that actually looks and feels like a comic book! It’s about time somebody decided to do this rather than recreate them and torpedo the film by putting their own “touch” on the concept.

This reverence for comic book art is what makes “Sin City” one of the most visually compelling films I’ve seen in a long time. While “Sky Captain” was overwhelmed by its own visuals, “Sin City” is enhanced by them. Some of these digital sets are, in fact, not very fancy at all. But they don’t have to be. After all, too many eye-popping scenes in a movie will make the whole thing seem dull.

There were only a handful of times that the effects or the pacing broke down, particularly in a nice little vignette about a cop killer and league of vengeful prostitutes. However, the stronger stories kept everything afloat nicely.

The acting is appropriately tongue in cheek. Mickey Roarke steals the show from Bruce Willis as the hard-boiled hero, while Elijah Wood and Nick Stahl turn in great performances as unlikely villains. Of course, the comic-book geek draw is going to be Jessica Alba, who is absolutely gorgeous. But Alba is one of those actresses better seen and not heard. Dancing on a stage in a seedy bar, she is a goddess, but when she opens her mouth, she becomes just another pretty actress from Hollywood.

Supposedly, Rodriguez is planning more “Sin City” installments. Let’s keep our fingers crossed.