I'm not going to bother with a complete review of the I Am Legend film, partly because many others have already done so. In short, though, the movie is excellent until the last five minutes. Will Smith does an amazing job in this moody action adventure tale about the last man on earth trying to save both humanity and his own sanity.

What really interests me, though, is the film's ending. As has been reported before, the director had to reshoot the ending because "the studio was unhappy with the film's finale, which is said to be very faithful to Richard Matheson's original story." I easily believe this report about how the movie was originally supposed to wrap up because there are numerous plot points setting up Matheson's ending. These include:

The fact that the film shows the Infected leader allowing himself to be burned by sunlight so he can glare at Robert Neville. This portrays the leader as moving beyond mere animal cunning, and possibly even caring about the capture of one of his fellow Infected. The incident is so unusual Neville comments about it later in the film.
The Infected showing increasing intelligence, including setting that snare trap for Neville. Despite what some viewers have suggested, that was not one of Neville's own snares. His snares used a black tarp to protect the captured Infected from the sunlight.
The "coincidence" of Anna arriving just in time to save Neville from the Infected. It's almost as if that was a set-up to discover where Neville lived. Also, why would she have been hanging out after dark in that area unless she was safe from the other Infected?
Anna showing disgust at how many Infected Neville killed for his experiments.

Because of these and other plot devices, the director was obviously aiming for Matheson's original ending (which would have been appropriate since it's one of the best finales in SF/F literature). Unfortunately, the studio decided that American audiences would revolt over such a bleak ending. The result is a finale which not only destroys the previous two hours of build-up and mood, but also leaves audiences feeling unsatisfied with the entire film.