Joan Fontaine. Laurence Olivier. Creepy Judith Anderson. Delicately filmed. Intense Bernard Herrmann music. It's a great gothic thriller romance and a Hollywood studio classic from the Golden Age so I don't want to find anything bad with it and can't find it either if I should try.
Alfred Hitchcock makes superb cake of his typical stylish mixture of genre: takes the base layer of simple love story, kind of reffering to standard hollywood melodrama, expands it to dramatic thriller, adds several drops of suspence and mystery, and ends with some didactic and unflinching ending. Everything is led by J. Fontaine's powerful performance, also stunning turns by L. Olivier, G. Sanders and J. Anderson.
"Master of suspense", sure, though suspense is something Rebecca could use more of. It more established Hitch as a master of psychodrama & masochistic romance—thus the rapturous metaphor of a timid girl who's given no name competing with a "perfect woman" who has a name but is never seen or heard. Only when the movie tries to cram an entire murder plot into the last act does it become too tidy. Trust the irrational.