Criterion says, "it has never been outdone for sheer psychological terror". AMC's FilmSite.org has an extensive plot description, calls it "darkly atmospheric" and says it's a "creepy, eerie gothic film". Vanity Fair calls it "an iconic film" and details the curse. The New York Times has a positive review, faulting it only as being not scary enough.
Roger Ebert gives it 4 stars and opens a positive review with this:
Roman Polanski's "Rosemary's Baby" is a brooding, macabre film, filled with the sense of unthinkable danger. Strangely enough it also has an eerie sense of humor almost until the end. It is a creepy film and a crawly film, and a film filled with things that go bump in the night. It is very good.Rotten Tomatoes has a critics score of 99%.