I Walked With a Zombie was pretty interesting. Definitely very unlike what we think of as a zombie film, and tending more toward thoughtful ambiguity than clear supernatural horror -- which makes it an interesting middle ground between Lewton's Cat People, in which the leading lady's were-cat nature was presented as pretty definitely real, and its followup Curse of the Cat People, in which the whole thing was pretty clearly in a child's imagination. Also, for its time, it's refreshingly non-racist. There is plenty of condescension toward Haitian beliefs from the white characters, but vodou culture is portrayed fairly realistically, the cruelty and consequences of slavery are addressed, and while the black characters are in traditional servant and exotic-other roles, they aren't played in a caricatured or demeaning way (a quality shared with the two Cat People films, each of which features a black actor from this film, Theresa Harris in the former and "Sir Lancelot" Pinard in the latter).
I found the ending rather abrupt. I guess the ambiguity of it was intentional, but it seemed to leave a lot of other stuff unsettled.