Hancock, my friends, was a fairly good movie. Like most movies of the current age, it could have done without a few things, one of which being the coarse language. Any parents bringing their children to this movie got hit by the f-bomb (well, it was only one). Plot-wise, it was good. Hancock morphs from a comic antihero in the first part of the movie to a compelling dramatic character in the second.
The movie made you think about a few things too, like what it means to do the right thing, what a hero really is, how to deal with superpowered misanthropes, etc.
Go see it, if you don't have kids and profanity doesn't bother you. Otherwise, I'd leave this tasty morsel of cinema alone.