Although made on a shoestring budget and as a sequel to The Awfull Dr. Orloff, this is a very enjoyable flick and a fine example of early Southern European horror. It's actually better than it's predecessor.
The plot is not real important (it contains a zombie-like creature, a castle and a mad scientist). What makes this movie is the mood, the often beautiful camera-angles, the art direction and the hints of later Franco movies.
For example, there's several scenes with women performing, often in erotic scenes, with men watching - which is exactly the kind of voyeuristic cinema Franco would turn to in later years (Vampyros Lesbos, Demoniac).
There's - of course - quite some nudity, which must have been considered quite risque in 1964. And there's a small cameo for the director himself, as a pianist who seems to be blind.....
Also of interest is the use of electronic devices used to make the zombie a murderous weapon, they give a strange effect to the movie and reminded me of early 50's sci-fi B-movies.
All in all, recommended for Franco fans and b/w horrormovie fans. If you've never seen a Franco I suggest starting with Vampyros Lesbos or Female Vampire.