“Spider-Man” was a great movie with a few serious problems. “Spider-Man 2” was superhero perfection. And “Spider-Man 3” is two steps back. At times deliriously entertaining, the film avoids a lot of blockbuster failings, but suffers from some seriously misconceived scenes and poor plotting, falling from the perfection (perhaps somewhat unfairly) expected after the first two films.

In “Spider-Man 3,” the gang returns to the trilogy for the third, and maybe final, film – franchises never stay dead. This time out, Peter Parker’s (Tobey Maguire) newfound success is alienating the Mary Jane (Kirsten Dunst), who just got dropped from a Broadway production after the first performance (ouch!). The couple’s intended engagement is further delayed by the discovery that Uncle Ben’s killer was not actually that guy from that other movie but a reluctant criminal (Thomas Haden Church) who just got transformed into a nigh-undefeatable villain of living, angry sand. That, and Peter’s prior best chum Harry Osborn (James Franco) has taken up the mantle of his father, the late Green Goblin Sr. To combat this new menace, Spider-Man is unwittingly bonded with a slithery parasitic life form that turns him a sleek black, but also makes him act like a dick to everyone. And sown throughout the film is the story of Peter’s conflict with hot shot Eddie Brock (Topher Grace) who, of course, eventually melds with Peter’s alien costume to become Venom, the villain everybody under the age of 16 really came to see.

Performances are solid across the board. Newcomer Topher Grace shines as Eddie Brock, Peter’s career and social rival, whose Stephen Glass-esque fall is sadly neglected in running time. And Sandman Thomas Haden Church’s craggy face and pained looks carry his character far beyond the meager script. But the real stars this time around Kirsten Dunst and James Franco. Mary Jane is finally more than doe-eyed kidnapping fodder, and Franco gets the chance to play the passive-aggressiveness of his character to its full pathos. If there is a weak link, it would have to be Tobey Maguire, who just doesn’t seem to move his characterization beyond what is well established. On the other hand, perhaps he’s just hamstrung by broad comedy and a constantly changing hairstyle.

No matter how harsh the hater, everyone has to concede to the sheer spectacle of the fight sequences. The battles are vicious, fast, and make brilliant use of changing goals, complications and clever action set pieces, from toppling cranes and falling wedding rings to a the construction site turned web-covered deathtrap that hosts the film’s final battle royal. Unfortunately for the film, the first fight scene, which has civilian Peter and Harry flinging each other about the New York skyline, is also its best. Which isn’t to say anything bad about the other fights – it’s just that, like the movie on a whole, they’re always dulled by the memory of the shiver inducing awesomeness of the first act.

The movie suffers from the full outbreak of a symptom hinted at in earlier film: serious inconsistencies in quality and tone. The movie’s sincere moments (Sandman’s gorgeous “birth”) mix with the contrived melodrama and painfully self-aware comedy like oil and water. Much and justifiably derided by film critics and back row grumblers alike are the “evil Tobey” scenes, in which the new bad Peter expresses his new badness with a black suit, beatnik lingo and inappropriate public dancing. But the film’s greatest stinker is an 11th-hour revelation that comes out of nowhere and is so awkwardly scripted and delivered that it stops the film cold. You’ll know it when you see it.

In the immortal words of the very mortal Uncle Ben, “with great power comes great responsibility.” Sam Raimi may have the power of a $350 million budget, but with that responsibility, and the expectations of some billion moviegoers, Raimi is slipping under the weight. And although “Spider-Man 3” drops as many balls as it catches, it is still head and shoulders above every other superhero movie, and well worth a sling for the webhead with expectations carefully checked.