The first thing to say is that the film is a great improvement on the original story, which I read out of curiousity. The author specialises in intentionally pointless stories about hopelessly damaged people, and the spanking is not brought in as any sort of positive development, but to bring an end to the heroine's first and only attempt at a normal life and job, after which she goes back to pieces. Turning this into a tale of redemption and happiness through BDSM is quite a creative achievement.

The heroine's self-harming could be seen as implying that BDSMers are sick puppies, but one could equally read it as showing that she is painfully incomplete until she finds her Dom. Both of them are weak and flawed people, but together they can be happy.

I don't see her actions as manipulative, more that she is actually the stronger partner but uses all her new-found strength in serving him. She knows he needs excuses to punish her the way he enjoys, so she obediently provides them. When he panics and can't face his need to keep her she forces the issue the only way a good sub can, by obeying him beyond reason, through pain and humiliation, till he has to see what a treasure he has if he dares to take it.

The final scene with the bug in the bed is a model for service-oriented subs. If she were playing games for her own benefit, she'd just leave the bed in a mess and get punished for that. But she makes the bed neatly, and then completes her perfect service by providing an excuse for what one hopes will be a memorable thrashing.

As Max says, it doesn't work as pornography, but that's like saying "Sound of Music" doesn't work as a war story. I think in the future this will be listed alongside such films as "Brokeback Mountain" in a genre of love stories outside the straight-vanilla mainstream, where the theme is the love story and the non-standard sexuality is just the setting.