I Am Legend

While the sun shines, it’s a four-star thriller with a superb turn from Smith. When the moon rises, it’s a two-star horror cartoon...

The movie works well while it's running, although it raises questions that later only mutate in our minds.

...it's a haunting film, a long-playing, hi-fi version of the 28 Days Later sequence where Cillian Murphy forlornly wanders the empty streets of London.