I seem to be alone in this, but I rank
Pet Sematary up with
Salem's Lot and
The Shining as one of King's greatest novels. In the sense of pure horror, it is one of his scariest but also one of his most serious. It is as much as a treatise on death and grieving as it is a horror novel. King outdoes himself in the area of riveting terror
and self-reflective thoughts on sorrow. It's a beautiful balancing act and, in my opinion, the one King novel you should not read just for entertainment reasons. Also, if any book needs the warning, "Don't read before bedtime", this is it.