This takes off from the same premise as Wanted, only here the reluctant superhero is a slob rather than a weed.
Will Smith stars as Hancock, a stumblebum boozer who also happens to be able to lift oil tankers and fly through the air. But the trail of damage that his crimefighting interventions leave behind has made him thoroughly unpopular in Los Angeles; he doesn't care, just so long as you don't call him an "asshole".
Then up pops an even rarer creature, Ray (Jason Bateman), a PR exec who's a decent guy; with his help, Hancock might become a nicer, gentler kind of superhero...
And do we care? Not at all, especially when the comic tone of the first half turns into a sort of Blade Runner-lite in the second. Director Peter Berg mounts a special-effects extravaganza that's very boring indeed, and doesn't quite deafen us to the inadequacies of the script, while Smith pretends to be a grumpy git but, naturally, winds up begging us to love him.