An oddly enough ride.
Hancock is enjoyable, but has three little drawbacks: Will Smith, the clumsy usage of visual effects and (how not so?) the script .
Although Will Smith has proven that he can act like an actual actor (see the heart-warming The Pursuit of Happiness), most of the films he gets involved in are just commercial blockbusters, with all their negative connotations (his first actual big-screen hit, Independence Day, may have set the tone...). And if he can get involved in the production (and he does again in Hancock) and show off a bit, better still. Show off chest muscles, or backside, or simply poses... You can tell he likes that. He shows off less minutes than in previous films, but he shows off. Just like in I, robot, or I am legend. Still, there's something about Will Smith's presence that stops you from hating him so much despite all this. Odd. Whether this is charisma or not, or whether this film should have been called “I am Hancock” is obviously not the purpose of these lines.
All the visual effects from the trailer and used as bait seem to happen rather soon in the film. Which is good, since they aren't anything special or unseen before. After that, for a moment, it seems the story will acquire deeply human overtones and leave effect in the background... but then the film takes an unfortunate and inexplicable path and we come back to visual effects ad infinitum. No surprises here.
But we also come back to a much darker atmosphere that changes the style of the film and that (again) seems to be uncalled for. There is a similar confusion with the genre itself: comedy, more dramatic at times, “adventure” parts, ... The surprising and unconventional approach probably comes from the intention of making a different superhero film. In practice, however, the producers truly seem indecisive about this, and so ended up creating a strange hybrid creature.
All the above, plus the fact that the relationship between characters is awkward and twisted results in, yes, an entertaining film, but one that doesn't make the most of itself or even reach the end of the story looking like it's the end of the story. If you are reading this in disbelief, go and watch it: the cleaners may have to kick you out, because you won't believe the film is over. As spectators, we are entitled to a fulfilling experience. And if a script doesn't give us this ultimate experience, then we feel emptiness in our film goer hearts. Subconsciously, we ask for more and we can't help cursing the experience.