The set design, lighting, and costuming all present a sort of Art Deco Gothic look that suits the material. Poelzig really is the leader of a Satanic cult. He also married Werdegast's wife after his imprisonment. And where is the daughter?
As with every one of the Karloff/Lugosi collaborations I've seen, the romantic leads are bland and forgettable, and the comic-relief bits are excruciating. Thankfully, Karloff and Lugosi aren't. Lugosi is uncharacteristically subdued here, possibly because he finally gets to play the hero. The movie looks great and has some nice, snappy dialogue ("Even the phone is dead" being my favourite one-liner). And there are dead women preserved in giant glass bottles and a high-stakes chess game! No killer apes, though.
The Poe elements are almost non-existent, limited pretty much to hints of heterosexual necrophilia and a black cat that wanders through at points to scare Werdegast, who suffers from fear of cats. Highly recommended.