The movie was pretty good - I won't spoil anything, unless you count giving away the plot a spoiler. So Mel Gibson is this guy, he works in an oil refinery, and he lives in South Dakota. Aliens come and burn pornographic pictures onto his lawn, and so he and Will Smith capture an alien scout ship and go up and plant a nuclear bomb on their ship and blow it up before it can get to earth, crushing the planet. It also has a segment starring Macaulay Culkin's younger brother, doing a horror-movie re-enactment of the movie Home Alone. An alien invader sprays his face with acid, and he puts his hands on his cheeks and yells. It's SOOO cute! Anyways.
The movie was what you might expect from the director/writer of Sixth Sense and Unbreakable - interesting plot, finely crafted direction, poor acting from the director in a cameo role, and a strange sort of distance from the movie and the audience. MNS played the audience like a master, though, you could practically see him sitting back and giggling and saying "Ok, time to make them scream! *bzzt* Ok, now I'm going to make them laugh! *bzzzt*". He knew how to push the audience's buttons, and push them he did - I can't remember the last movie I've sat at where the audience was so vocal, laughing, jumping in their seats, etc.
Overall, I'd recommend it. It's pretty good - a bit odd, but good.