This is a very lovely, romantic and witty film.
This is a film about a woman getting spanked. And loving it.
The very fact that both the above statements are true sums up how gracefully the filmmakers have met a very thorny challenge. Even when Mary Gaitskill's original short story was written - well before a much-increased awareness of sexual harassment in the workplace - this subject matter was likely to invite criticism. Yes, even then, some people were aware that others (no one they knew, but… they'd heard about such people) liked a little pain. Hell, a lot of pain in some cases. The big difference here of course is that this is taking place in an office, and that the male boss is inflicting this pain on his female employee.
So, why does it work? Excellent casting to start with. Maggie Gyllanhaal's pert, almost Victorian face expresses a wide range of hidden currents with minimal movement. James Spader somehow has managed to play a range of sexually unconventional characters without ever losing a certain air of Everyman decency. Jeremy Davies as the main character's nominal boyfriend, Stephen McHattie, as her alcoholic father, and Leslie Ann Warren as her suffocating mother are all vivid and authentic, but the focus here is firmly on the two wounded people who discover each other in a most unlikely way.
Because another thing that makes it work is the absolute complementarity of their needs. The physical relationship may be clearly dominant-submissive, but the emotional relationship is about as caring and complex as you can get. As the main character's desire to submit becomes more and more insistent - yes, even domineering -, it's clear that she's as concerned with piercing her boss' terrible isolation as much as meeting her own needs. He in turn uses his dominance for benevolent purposes: curing her self-mutilation with a single command, coaxing her into (ironically) assertiveness, demanding, in effect, that she be an individual.
All this told with great visual beauty and humor, and a certain exuberance in exploring the edges of its subject, notably a series of bad dates, submissive style (yes, even submissive women have trouble finding the right dom.) But above all, and this is at heart the key to its success, told with love.