The Blind Side is the kind of movie that by custom I absolutely hate, and I sort of vaguely, not at all to excess but distinctly and undeniably, enjoyed watching it anyway. That is your rave for the evening.

It's one of those movies that uses the phrase "based upon a true story" like a cudgel: if it is a true story, it is the kind that has an awful lot of fuzzy-wuzzy Hollywood clichés strung along it, to a degree where you almost refuse to believe that it wasn't mostly invented by a screenwriter using a real-life scenario as, at best, a springboard. And yet... and yet- truth is stranger than fiction, they say, and they are right; and could it not be that things in life happened exactly this way? It could. So one feels guilty not giving the film the benefit of the doubt, which it of course does not deserve, because when all is said and done it is just another of those damnable "underprivileged youth comes up from the streets to find success in sports" movies, although dammit, Michael Oher of the Baltimore Ravens did come up from the streets to find success in sports, much as the film depicts, and so what if some of the more thematically fragrant details are lies?

When I am dictator-for-life, there will be no more fact-based movies. They get too complicated to deal with.

Whatever the facts of the matter, the movie is this: a wealthy Memphis interior designer, Leigh Anne Tuohy (Sandra Bullock) takes pity one cold night on Michael Oher (Quinton Aaron), a wildly underperforming student at the prestigious private Christian school that her daughter Collins (Lily Collins) and son S.J. (Jae Head) attend; she gives him a warm couch and warm meal, after weaselling the truth out of him, that he is homeless, starving, and wearing the only clothes he owns. After consulting with her husband, Sean (Tim McGraw) - that is to say, informing him of her decision, and allowing him to accept her lead without complaint - Leigh Anne takes Michael in as a permanent member of the family, eventually adopting him and encouraging him to pursue a career as left tackle on the school's football team. Michael proves so endlessly talented at the game that he soon becomes one of the most sought-after players in the region, fielding tens of offers from great Division 1 universities; and thus it comes to pass that he must raise his grades from a basement-level GPA in order to secure a scholarship. I'm not giving anything away if I say that he does this, because after all, he is a player on the Baltimore Ravens now.

The Blind Side is only incidentally a sports picture; largely, football is used as a metaphor for family. The job of the left tackle, as Leigh Anne puts it in a film-opening monologue set to 1980s NFL footage, is to protect the quarterback's blind side, to have his back in other words. The quarterback may be the heart and soul of the team, but he needs that fellow linesman to keep him safe, and allow him to do his job. So it is with family: nobody can succeed all alone, and it takes someone like Leigh Anne to watch Michael's back, and make sure he's able to thrive as best he might. That's an awfully soppy metaphor, and if that were the whole of it, I can't imagine that the movie would be even a little bit tolerable.

What saves the movie, insofar as it is saved, is the absolute commitment of the cast, and writer-director John Lee Hancock (who hasn't made anything since the dire 2004 epic The Alamo), all of whom either don't notice or don't care how very pwecious their scenario is. Sincerity is just about all The Blind Side has going for it, and I suppose for some viewers better-inured to such things than myself, the movie will never be more than a cloying Oscar-hunting biopic (at the same time, as attested to by the film's luminous box-office performance and the testimony of a good friend of mine - no cinephile he - who thinks this one of the better movies of the year, plenty of people find that sincerity far more than enough, and love the movie without my rather pronounced feeling of self-loathing). But sincerity ain't nothing, particularly given the number of similar heart-warming underdog tales that are plainly mercenary in nature.

Surprisingly, it's Sandra Bullock who gives the film most of its heart and spine, in a steely, presence-filled performance that lacks any of the irritating affect that I am used to associating with that actress. That she's kicked up some Oscar buzz speaks more to the predilections of the Academy than the quality of the work, but for Sandra Bullock, this is fairly excellent stuff: strong, resourceful, humane and loving; we can't call the situation unbelievable, because it happened, but it fairly is unbelievable that a woman like this would decide on the spur of the moment to take a large, barely articulate African-American youth into her home and family, but the way Bullock plays the character, it actually seems half-way reasonable that she'd do just that.

In the main, The Blind Side plays it as safe as possible: the ending is plain by the time the studio leader ends, and all the sociology and cultural issues are kept nicely boxed-up and apolitical. If racism and classism are brought out, it is only to safely assure the viewer that no, we are not like that, and nor are our characters, and nor are you, our audience: the film presents a vision of race in America that is roughly 180º from Bullock's last message picture Crash; but it is similarly soothing to the prejudices of its audience (which it presumes to be white, middle-class, and Democratic).

Nor does Hancock or his crew (including a slumming Carter Burwell writing the score) do much with the material besides present it: there are maybe more close-ups than I'd have expected, but it is not a particular fancy or prestigious work of craftsmanship. This is moviemaking strictly according to the books, pitched right square at the middle of the road, a drama that nobody can flat-out hate because it doesn't do anything ambitious or edgy. Given that goal, it is successful; and as far as heartstring-tugging real-life sports dramas go, The Blind Side is certainly not an example of the worst of its piddling genre. It gets the job done without being too crassly emotional, and I suppose it's unfair to ask it to be anything else.