For long-time fans of Marvel Comics, it’s nice to see the industry’s most venerable imprint finally getting the cinematic respect it deserves.

Marvel’s superhero titles have always been more intelligent, more willing to deal with pressing social issues and more enjoyable for the adult reader than superhero titles released by its main competitor, DC Comics.

“Spider-Man 2,” which opens today, represents Marvel’s flagship property well. Like 2002’s “Spider-Man,” the sequel is careful to blend familiar themes and characters from the comic book with solid movie storytelling, ensuring a film that is accessible to comic book fans and non-fans alike.

The sequel begins some time after the end of the first film. Peter Parker (Tobey Maguire) is now in college, his friend and sometime rival Harry Osborn (James Franco) is running a huge company and his longtime crush Mary Jane Watson (Kirsten Dunst) has a budding career as a model and actress.

But trouble is looming! Harry is bankrolling Dr. Otto Octavius (Alfred Molina), a mad scientist who is working on some kind of barely controlled fusion reaction. Predictably, this goes awry, and Dr. Octopus is born when four manipulating tentacles are fused to Octavius’s body.

The decision to cast Molina as the villain was a wise one. Like Ian McKellan as Magneto in “X-Men” and Willem Dafoe as the Green Goblin in both “Spider-Man” films, Molina brings a subtlety and depth to his portrayal of a comic book villain that other, more cartoonish actors could not aspire to.

The principal difference between “Spider-Man 2” and its predecessor is in its mood. While the first film often threatened to bury itself in gloomy, maudlin melodrama, the sequel acknowledges the pure joy that Peter feels when he puts on the mask and swings off to put the smack down on some evildoers.

With its PG-13 rating, there’s not much room for libertinism in “Spider-Man 2.” The romance between Peter and Mary Jane is less forced this time around, but we don’t get the sense of Peter being quite as much of a gay blade as he is in the comic book.

Under Sam Raimi’s direction, “Spider-Man 2” has turned out to be a model for how to continue a superhero movie series.