I’ve been bad and deserve to be punished: I didn’t mind the "50 Shades of Grey" movie.

In fact, director Sam Taylor-Johnson’s highly anticipated big screen adaptation – the first in a soon-to-come trilogy, and most likely quadrilogy considering Hollywood’s tendency to double its pleasure with a series’ final book – is probably the best possible movie to be made from E.L. James’ source material. Considering its origins are in erotic "Twilight" fan fiction, the bar isn’t exactly set high, but overall, there’s a surprising amount of cinematic pleasure to be found in "Fifty Shades of Grey" – plus an unfortunately predictable amount of pain.

Dakota Johnson (Justin Timberlake’s Stanford one night stand from "The Social Network") stars as the improbably named Anastasia Steele, a young college literature student and human sheet of tissue paper, quietly pushed and blown around in whatever direction.

The latest gust blows her to the office of Seattle sophisticate and businessman Christian Grey (Jamie Dornan of BBC’s "The Fall") for her roommate’s college newspaper interview. After admiring his huge … building, the interview commences. Lips are bitten. Crappy interview questions and awkward flirtations are passed back and forth. He smolders; she stutters. He offers her a long, hard … pencil. After the interview’s all over, nature’s smoke detector goes off, raining all over steamed up Ana. Because obviously it does.

The two begin a kind of courtship, but as Christian bluntly notes, he isn’t particularly the romantic kind. Dates aren’t really his thing. He’s emotionally cold and distant, due to some dark past that left him with little burns on his chest. He has a very intense and demanding set of rules, involving what Ana can and cannot eat or drink, where she must sleep and so forth.

And then there’s the sex dungeon.

Yes, coming as a shock to our young virginal lead and only the most pop culturally unaware in the audience, Christian is into S&M (as the MPAA pearl-clutchingly calls it in its official rating, "unusual behavior"). And now he craves Anastasia to be the latest submissive Juliet to his dominant Romeo. He just needs her to give in to his sexy, sexy … paperwork to make it official.

This is the main source of drama for the female power fantasy – really, it's a woman enforcing her control over a powerful bad boy – that is "Fifty Shades of Grey." That’s right; the big sexy movie event of the year is technically focused on legal documentation, a sexual contract that legally binds her to, well, being bound. Will she sign the contract and fall deeper down into Grey’s world of fancy toys of all sorts of recreational activities? Will she turn him down? Or could her sweet contorting innocence unshackle his chilly, controlling heart – and herself in the process?

It’s all very silly and overwrought … but for the first two acts or so, it’s also surprisingly kind of fun. Kelly Marcel’s script is more self-aware of its erotic camp factor than expected, and as a result, in the early going, "50 Shades" is flirty, entertaining and even funny – intentionally so too, a rare feat for these kinds of steam engines.

Much of the credit for the film’s success goes to the movie’s impressive Johnson … ahem, Dakota Johnson, that is. The daughter of Don Johnson and Melanie Griffith, the young actress has mostly worked in small roles ("21 Jump Street," "Need for Speed") and cancelled sitcoms (Fox’s "Ben and Kate"), but after her work here, she merits being a star.

She brings a shocking amount of breathy humanity and charisma to an otherwise wafer-thin movie, nailing every little flirty joke and making every new discovery register. As she continues her descent down the rabbit hole – complete with an eat me-drink me "Alice in Wonderland" reference – it’s Johnson that makes the audience feel the excitement and tension of these new discoveries and sensations. She almost makes you care how this S&M-tinted soap ends.

It's certainly not because of Dornan. Devoted fans weren’t too pleased with the casting choice back when he stepped in for first pick Charlie Hunnam, and there’s not much in the final product that will convert fans to his Christian-ity. To be fair, the role is near impossible; he’s essentially an inanimate bad boy sex fantasy, a somehow more creepily controlling and less human cousin to Edward Cullen – and he was a sparkly teen vampire.

On the page, he’s simply a handsome, sexually proficient nothing; on screen, Dornan brings little more to the table. There’s no charm. There’s no danger. There’s no wound. It’s nary impossible to see what Anastasia is supposed be attracted to here, and considering that’s kind of the crux of the drama – whether this guy is worth the potential whippings – the story falls kind of, well, flaccid.

Not that there’s much worthwhile drama to begin with. After a big contract meeting scene, where the two negotiate the fine sexual print and Ana asks what a buttplug is (seems pretty self-explanatory … ), the fun and flirty chunk of "Fifty Shades" becomes fairly aimless and kind of a bore.

The movie just runs out of stuff to do (especially with the ending, which basically scampers out the door as fast as it can after the climax). Characters like Christian’s family –including pop star Rita Ora – are introduced with no purpose. The lead duo bounds around a couple of new locales.

The only thing keeping the movie going is Christian’s still insistent contract nagging, which turns into some ponderous melodrama involving tortured pasts and punishments present. And drama isn’t quite E.L. James’ strong suit. Nor is dialogue, which, even after Marcel’s script work, is universally dopey and stilted. When the movie is fun and goofy, it just makes the softcore soap bubblier, but as the movie starts to take itself seriously and tries to come up with somewhere to take itself, it becomes more of a tedium.

There’s still something oddly watchable about "Fifty Shades of Grey," which is much more than I expected to report back. Johnson gives a star-making kick of a performance. Taylor-Johnson does a fine job directing, giving the film a clean, cool and smooth aesthetic – with the aid of Oscar-nominated cinematographer Seamus McGarvey ("Atonement," "Godzilla"). The rose-colored contract meeting is a warm visual highlight.

Her biggest shortcoming is, well, the much-ballyhooed kink. For all the pearl-clutching and think-piecing, "50 Shades" is pretty rote, barely reaching a simmer during its sex scenes. Part of the problem is that the male half of the equation seems as human as one of his sex toys (and, in classic MPAA double standard form, Johnson earns most of the nudity duties while Dornan gets to go mostly clothed in just the worst pre-ripped jeans). The other part is that the movie seemingly holds the sex and S&M material with tongs in the hopes of not getting infected with deviancy.

And, really, this is what we’re all up in arms about? In a time where the kink-happy "American Horror Story" has four well-watched seasons and "Girls" opened up its latest season with Peter Pan herself getting her butt nommed, this fairly tame material is riling everyone up? Cameron Diaz had sex with a car two years ago. You could see this bondage stuff on an average episode of "Criminal Minds."

In the end, either in terms of quality sex or quality cinema, "Fifty Shades of Grey" is nothing to get too hot or bothered about.