Most of the time, I'm in general agreement with critical consensus. Hancock is a big exception; I liked it quite a bit, while IMDB users gave it a 6.6 (Get Smart got a 7.0), and Rotten Tomatoes scores it at 39%. (Get Smart: 53%)
The titular character is played by Will Smith: Hancock has superpowers, but as a superhero, he's lacking. He's an obnoxious drunk, and totally uncaring about the collateral damage to property and bystanders he causes during his clumsy efforts to do good deeds, thwart bad guys, and save people. He lives a lonely and miserable existence. In a running gag, most people call him "asshole" to his face.
But one day he saves the life of Ray (played by Jason Bateman), who is the most decent public relations guy imaginable, heavily into do-gooderism and an optimistic believer that he can turn Hancock's life around via tweaks to his appearance, attitude, and demeanor. Hancock also gets roped into Ray's family: his beautiful wife Mary (played by conveniently-beautiful Charlize Theron) and cute son Aaron.
There is a lot of humor in the movie, playing off Hancock's misanthropy and obliviousness, Ray's earnest PR-babble, and their mutual fumbling attempts at rehabilitation. (And there's a hilarious description of the origin of "Red", one of the villains.) This worked for me, but—see critical consensus—it doesn't for everyone, and may not for you.