No need to echo consensus points on this outstanding horror movie production. My only gripe is with the recurring anti-climaxes that cheapen the original infernal effect. As a result, movie buffs are again shown that knowing when to stop can be as important as knowing how to start; at the same time, the horror flick certainly knows how to slam-bang start.
To me, two themes in the script's subtext stand out. First, key to many ace horror flicks, such as The Thing (1951), and Invasion of the Body Snatchers (1956), is not just the horror of the menace but the frustration in getting dis-believers to finally come around to confront the para-normal menace. Here, understandably, no one believes stories about an infernal kid's doll that's somehow alive. This, fortunately, adds to audience sense of engagement with Mom and little Andy as they're forced to grapple with the horror of the para-normal that no one else believes can be real.
Second is the poignant portrayal of Mother Love as that natural bond confronting the infernal doll in its death dealings. Ironically, it's the distance between mother and son at the outset that drives young Andy into the arms of what seems a friendly doll that will then be his needed companion. Thus Mom in particular must learn a lesson about family ties that the doll ironically provides. Happily, the growing bond between them is developed in a non-sappy way that's unusual for most any kind of movie. And that is largely thanks to actors Hicks and Vincent, respectively. In fact, I'd be inclined to award them special Oscars for their moving performances, as though the snooty Oscars ever took note of little horror flicks.
Anyway, these are two notable aspects of the screenplay neither of which has directly to do with the scary effects, but do merit mention. All in all, except for the anti-climaxes, the movie's superior of its kind, so catch up with it if you can.