Verdict:

Either the director or the script writers must’ve been high when they were creating this one. As I write this, I wish to be able to write more than a few lines, but after that first line, anything else seems to be redundant.
Throughout the movie you keep wanting to ask “what?” over and over. Perhaps if you put the story on paper it wouldn’t read too bad, but the execution thereof seems to be a little trickier. A question arises whether some scenes and lines were really necessary. Surely there’s something more useful to be said and shown at that time. The plot is not complicated but nonetheless twisted, and at every turn the inertia wants you to go one way, but the movie has already decided to go the other. Because of all the turns even the acting of the high rollers comes under strain.
The idea of a bum superhero sounds really good. So many places to go with it.
Have you ever met a homeless man? Generally speaking, they exhibit a certain type of behaviour. They have a lack of self-confidence, crusty lips and perhaps a broken walk from the drug addiction. Will Smith, as good of an actor as he is, does not show this behaviour. His ego is written on his face. He can’t not be charming. He is fit. With other words, he looks like Will Smith dressed as a homeless man costume rather than an actual homeless man.
Perhaps it would have been wise to split the movie in two and make two separate parts, with the first one only concentrating on Hancock’s journey from a bum to a superhero. It would’ve been a good movie and much easier to stomach.
In any case, what no one can take away from Hancock is that it’s a fresh drink of water in the long line of cliché superhero formulas. It’s hard to predict what happens next. And with that freshness you still get a good amount of laughs and special effects.