I've seen this once or twice before, and it always fell a bit flat for me for various reasons. That said, upon rewatching it, I can appreciate it just a tad more. The biggest problem for me is how sentimental and sappy the film can come across as. Sure, it might have been hard to keep the original ending from the book in a time when happy endings were all the rage, but I think the end product would have made the film more menacing and less sappy.
Speaking of which, while I love the suspenseful music the movie has to offer, the 80's love/drama music can get a bit on the cheesy side. But that's the 1980's for you, I suppose. There's also the fact the film drags a bit. Sure, it's normal length-wise, but it's mostly a drama for the first fifty minutes (and I don't know how interesting I found the whole affair issue, to be honest), and while the horror element is good when it gets there, the payoff doesn't erase the set-up.
The actors and actresses are solid, though. Standouts include Dee Wallace, Daniel Hugh Kelly, Ed Lauter, and Jerry Hardin (not so much due to his role or screen time, which was minimal, but due to the fact he plays Deep Throat 15 years later in The X-Files). Oh, and the makeup for Cujo was excellent. Though I know that Wallace had no choice but to fight Cujo off, I can't help but feel bad for the dog.
In the gore department, there's a few offerings, though not that many compared to other films of the time. Cujo can be a bit heavy in the drama department, which I think is why I underrated it before. For all it is, it's great portions and flaws, I think the film's just slightly below average. Decently fun, still. 6.5/10 (rounded down to 6/10 to fit site's format).