Here's my post from a few years ago on The Last Man on Earth, the definitive movie so far based on Richard Matheson's novella I Am Legend.
Don't bother with that Will Smith timewaster--it's a dumbed-down, Hollywoodized version of the story. Some of the early atmosphere is poignant and makes you think it's going to be a credible update of Matheson's tale of unrequited grief and political obliviousness but then it turns to ultra-fast CGI zombies hurling themselves at the camera.
The zombies change from smart to dumb and back again with the scenery.
It's another case of coked-up tinseltown screenwriters not telling a coherent story and wrapping it up with feelgood cliches (Akiva Goldsman may not actually be coked up but certainly writes like he is, having previously jabbered out the empty voids Lost in Space, Batman & Robin, and I, Robot).
Why can't the current adapters trust Matheson? Just go on autopilot and let him tell the story. He's a whiz at spinning yarns--he wouldn't end the story with "the hero sacrificing himself so that a theretofore unknown colony of survivors could go on."
He'd have a gut-wrenching sociopolitical twist, or something.