On very few occasions, I am able to say, "I enjoyed the movie more than the book." I Am Legend is one of those few exceptions. Maybe it's because the Will Smith version was not the first attempt to get the story right on the silver screen. Honestly, I don't remember The Omega Man enough to offer a fair comparison, but just comparing the Will Smith version to the text--the movie kept the monsters scary.
So, after reading I Am Legend, I wondered why I never felt afraid while I read. Certainly, Matheson wanted to create a creature that was realistic and terrifying, a mix of new and old, a combination of science and legend. So, where did he fall short? The phrase that keeps bouncing back into my mind is "body glue." This strange biological manipulation of the fictional bacteria within the host organism sounds more like a child's toy slime than a terrifying feature of an unstoppable demon.
Matheson's pseudo-scientific explanation for the vampires in his story is reflected in the phrase "body glue." By mixing creatures of lore with science, Matheson loses the mystery of the fiend and leaves a story full of gobbledygook that is either too unrealistic or too outdated to take seriously. I think the hardest pill to swallow was trying to accept that vampirism was created by bacteria. Bacteria is a simplistic species, and as far as I know, not capable of much more than reproducing; altering the characteristics of larger species seems impractical. Viruses, however, do alter larger species on a DNA level, and even today little is known about viruses (origins, why they exist, if they're living or dead...). I'm not sure why Matheson settled on bacteria over viral infections, but the story lost a lot of potential in that decision.
The scene with the dog is also important to point out. The film version uses pathos to connect the audience to Will Smith and his heroic canine. The written version leaves readers ambivalent. In the movie, Will Smith has the dog from puppyhood; in the text, the dog appears rather late and leaves rather quickly. Readers do not have the emotional connection as the disease consumes him. The text doesn't even show the disease consuming him. The story has Neville abducting the dog, whispering sweet nothings into its ear, and then the story leaves off with a passive sentence: "In a week the dog was dead" (100). Matheson's decision to cut off the dog's life with a passive line leaves readers feeling passive toward the dog, seeing him only as a means to foreshadow that living vampires are able to walk around in sunlight.
And then there's the ending. Although I didn't completely appreciate the religious undertones the film version offered regarding faith and survival (and butterflies), the slightly optimistic end worked better than Matheson's mutation into another genre. The novel ends with Neville being brought into a new world order to be executed. Out with the old, in with the new, apparently. I believe Matheson was toying with the concepts of alteration and the reversal of mankind being the monster, but I think his theme changed too drastically. I suppose this portion also reflects the omnipresent fears of the Cold War at the time of publication (the war that brings the disease about also hints at these fears), but they did not mesh with the fears found through the rest of the story. Although Matheson has an interesting story regarding Cold War fears, it's a story for another book. He lost sight of what I Am Legend was really about: the definition of a monster.
I don't want to end with anyone thinking I hated the story. There were several parts that worked very well (when Neville buries his wife and she comes back from the dead), and the premise is genius. If it weren't, the movie wouldn't have worked as well as it did. Still, I expected more.