I saw Fifty Shades of Grey last week and I liked it. May God forgive me. I should be taken out and flogged – which would at least be appropriate.

Given the worldwide controversy, denunciations from feminists (a number of whom admit they haven't seen it), campaigns on social media and general hubbub, buying a ticket felt a bit like letting the side down. I expected a piece of trash; five more lashes to me for prejudging it.

The movie I saw was sober and thematically rich. I didn't find it that erotic, but I'll admit to a little swooning. British director Sam(antha) Taylor-Johnson (Nowhere Man) has ensured that it is gorgeously photographed, with sensuous lighting and delicate close-ups. A beautiful young woman, played by Dakota Johnson, enters a dangerous relationship with a rich man (Jamie Dornan), who's somewhere between a model and a psychopath. Some of the criticisms are fair, but misleading. Yes, it does conflate the tropes of romantic fiction – the heroine who falls for a stranger who's worth $2 billion and flies a helicopter – with an abusive relationship, but surely that's the point? If the film is about anything, it is about consent and coercion, in its many forms. Fifty shades of power, in fact.

Anastasia Steele is attracted to someone she wouldn't normally go near. Christian Grey is a little older, vastly experienced in sexual matters and incapable of love – all of which he makes clear at the start. She is about 21, a virgin, smart as a whip and fully capable of looking after herself – no victim. I haven't read the books but I'm guessing that a lot of the readers connect with this depiction of a modern woman struggling with the tension between doing what's good for you and taking what you desire.

Ana resists him, but her heart says "this is the one". He pushes her away, saying 'I'm not the man for you". Yet he can't stay away from her either. At every step, he warns her of his exotic tastes, his inability to do "romance". He even shows her his "play room" before they get past kissing. He also showers her with expensive gifts and tries to control her life, most of which she finds troubling. She won't be bought. Diamonds are not this girl's best friend.

Ana has to choose what kind of pleasures she will accept. Christian makes that very clear when he insists on a kind of sexual contract. They go through it, item by item, in an erotically charged and funny "business meeting", where she rules things in or out. Fisting of any sort? "Not under any circumstances," she says. "What are butt plugs?" she asks. Her innocence attracts him; his experience attracts her. Not one second of the film is coerced. Each act is consensual – which is not to say that Ana finds it all to her liking. She walks out a couple of times, but keeps coming back – just like Bella in Twilight, which is the origin of the idea for E.L. James' best-selling novel.

It started as a piece of fan fiction, with bondage and discipline instead of vampirism. James wisely took the girl's age up to 21, the age of consent. Christian's outlaw sexual tastes give the story tension. Bella risked her life to love Edward; so far Ana has just risked a sore bum and major damage to her heart.

E.L. James brings this back to a real issue. Ana falls for a man who can't love; he won't even let her touch him. Christian's problem isn't really his need to dominate – it's his fear of love (apart from the fact that he's a prize control freak and a genuine arsehole). That's where the story hits every girl and woman with something she already knows: men are cowards about commitment.

Most of the feminist criticisms appear to my reading to be based on the way the books (and now the film) make all of this so pretty. It's an abusive relationship dressed up to look like something desirable. Well yeah, otherwise Ana would never have to make hard choices. He's grooming an innocent; he's a classic abuser. Yes and she sees it. Implicit in that criticism is a belief that the women going to see the film (in the millions) can't see that for themselves, and can't defend themselves from this insidious confusion.

I don't mean to be rude, but that's what the censors among us always say about movies from which they want to protect us. You and I may be smart enough to see the irony/artistic worth/subtle messages of this or that film – take your pick, from Pasolini to Catherine Breillat – but it's the young ones who are at risk.

I think what some of these critiques are saying is they don't like the way the movie normalises porn for women, which is not the intent of the movie I saw. Pornography has a completely different aim and a lot of it is demeaning for both sexes. Fifty Shades dares to say that sex, even of an exotic sort, can be a lot of fun, and so far, the series is about where Ana draws the line. She says no several times, and Christian stops what he is doing immediately.

No really does mean no in this movie. I thought that was a message we had all agreed upon.

Twitter: @ptbyrnes