While it had its flaws, I'd enjoyed the 1964 film The Last Man On Earth (with Vincent Price), like this film based on Richard Matheson's 1954 novel I Am Legend (which I haven't read), so I was curious to see what this treatment was like. This film, however, didn't have a whole lot to recommend it despite a few nice moments.
Will Smith stars as Robert Neville, a virologist who failed to prevent a cure for cancer mutating into a hideous disease which killed most of the population, and turned the rest into ravening zombies, except much speedier than 'zombies' would normally imply. Neville, who may be the last survivor, and whose wife and daughter may be dead, is still working on a cure in post-apocalyptic New York, with only his faithful hound for company. One of the film's worst scenes involves the death of said canine. There's also an awful, bathetically angsty scene between Smith and some mannequins (seriously).
I'll admit that I like Will Smith; he's got an easy charisma that's rare among male Hollywood stars. And he's certainly smoking hot in this film - we get to see a lot of flesh, though nothing too intimate - this is Hollywood, after all. However, as other reviewers have noted, in this film, playing such a tortured role and without (for the most part) other characters to bounce off, his charisma (his strong point) is muted. Another flaw is the completely illogical plot; why, for example, does Neville still have access to electricity and running water for his experiments? This example could be multiplied many times over.
A more serious issue is the not-so-subtle Christian propagandising the film engages in throughout. I really didn't appreciate being evangelised to in this propagandistic, concealed way.
Strengths? The aforementioned Will Smith eye candy - and there were some very nice, atmospheric scenes set in an abandoned New York city (though in conception that's nothing we haven't already seen in 28 Days Later, a more interesting failure), and also in Neville's underground laboratory. But overall, I'd stick with The Last Man On Earth.