According to Stephen King, he barely remembers writing Cujo because he was drinking so heavily at the time, and I remember the book reading like it was written by someone who didn't know what kind of story he was trying to tell -- although admittedly I don't remember it all that well since it was such a long time ago (I was, however, sober). The movie version of Cujo, directed by Lewis Teague (who went on to also helm Cat's Eye two years later), streamlines King's story a bit, but by cutting out some of the extraneous subplots, it just emphasizes further how little there is to the story. Everyone knows that Cujo is about a rabid dog terrorizing innocent people, but it's a little surprising to watch the movie and see how long it takes for those events to actually occur.
Before we get to Donna (Dee Wallace) and her young son (Danny Pintauro of later Who's the Boss? fame) trapped in a car that won't start while the homicidal Cujo stalks their every move, we have to spend a long (long, long) time with Donna and her husband as they deal with their personal and financial troubles: She's having an affair with a moody carpenter, while he's about to lose a big client at his advertising firm. (Snore.) Building up characters over time can work well in a horror movie, so that when we finally do get to the terror, we care about what happens to these people and understand what makes them tick. But the domestic drama in Cujo is so anemic that all I was doing was counting down the moments until Cujo started tearing into people's flesh, which takes until at least the halfway point of the movie.
There's nothing supernatural going on in this story, and the way that two mundane things (a broken-down car, a rabid dog) can combine to create a horrific situation is portrayed effectively. The scenes of Donna and her son panicking as their options quickly dwindle are intense, and Wallace does a good job of creating empathy for her character (even though she's sort of being punished for her thoughtless affair). There's not enough of a connection between the earlier drama and the later horrors to justify all the time spent at the beginning, though, and the way that Donna's husband (Daniel Hugh-Kelly) symbolically heals their marriage and forgives her by coming to her rescue is a little retrograde and simplistic.
Then there's Cujo itself, which despite some heavy make-up work still looks like a fairly placid St. Bernard. It's easier to make a dog look menacing than it later was for the creators of Graveyard Shift to make rats look menacing, but there are still times when Cujo seems more cuddly than dangerous. I would have preferred a better sense of agony and terror from both the animal and the human characters, rather than a bland soap opera followed by scattered moments of genuine suspense.
How far to Castle Rock:Cujo is one of King's main Castle Rock novels, and the movie takes place there as well, although there's only one brief moment to indicate the setting, and the town as a whole doesn't really play a part in the story.