That's one bad dog.
Before Stephen King's novel, Cujo meant nothing. Now you can use that word to refer to a dog and anybody - even people who have never read the book or seen the movie - will understand what you're getting at. Imagine having that kind of cultural impact!
I still can't decide if adapting Cujo was an obvious choice or not. There's something cinematic about confined spaces, and much of the story takes place inside a car. But the scary dog on the page doesn't always translate on screen. As a novel Cujo is one of the more inspired coke-period King books - it's just got pages and pages of absolute nonsense that has nothing to do with the main plot - and a lot of that strange, delightful bloat can't make it to the movie.
The trailer is interesting; I like the blood drop motif. I wish trailers would still do stuff like that, have little visual motifs. There's no room in the modern fade-in/fade-out trailer aesthetic for that, i guess.
I quite like the original poster for Cujo; the farmhouse and blood-spattered picket fence make you think this could be some sort of heartland horror/Texas Chainsaw-esque thing. The dog isn't sold whatsoever.