The Serpent's Egg is almost universally panned because it bears the signature of Ingmar Bergman, yet it doesn't feel much like a Bergman movie - except in a couple of flashes.
Most of the movie is set in dark, humid and chilly inter-war Berlin, where the protagonist gets ever closer to a sinister revelation. This side of the movie feels a bit like another bleak 70s artifact, Soylent Green. When David Carradine gets - at last - hired as an archivist in a sinister clinic, the viewer's interest is piqued.
However, Carradine is saddled with a sister-in-law, Liv Ullman, who comes along with a different set of scenes, that recall Cabaret without the acrid verve of the original. Liv Ullman tries hard, but she is truly miscast. Jane Birkin would have been perfect in this role.
The dialog is poorly written and gives the movie the choppy quality that everyone has objected to. The lines sound translated, unnatural, and David Carradine can't be faulted for sounding lost.
The big budget is well spent, and the film is not boring, nor pretentious. Some effects are in poor taste (the opening credits, and an excruciating scene in a brothel).
I suspect that The Serpent's Egg would have a better reputation today if it had been signed by a lesser director, say, George Pan Cosmatos. Without changing a single shot, it would be remembered as an interesting attempt at something different.