Bunuel is one of the greatest moviemakers of all times and this is his best work.
Mordant, funny, ironic verging on sardonic, yet occasionally sympathetic to the
plight of its characters, and unfailingly artistic throughout.
Many single frames would by themselves win photography prizes -- the composition,
lighting, and rich B&W tones are simply gorgeous.
As in almost any Bunuel movie, there is no real story; instead, using nearly
only images (this could work as a silent movie), Bunuel tells us a parable
about bestial and noble actions, about the delicate nature of the veneer of
civilization, about mob behavior and moral virtues,
all crystallized in the light of an apparently supernatural condition
(hence the "angel" in the title).
At the end, Bunuel pulls one of his signature surprises on us, perhaps to tell us
that the rather wealthy and mostly vain people whose behavioral responses were
just illustrated under his camera's eye are just a random sample of humankind.
B&W movies do not come any better than this.