IMDb and Wikpedia state Pupilo allowed Ralph Zucker to take credit for direction. This is an incorrect reading of the Italian credits. They read diretto da Ralph Zucker, literally "direct from" as in "presented by." The last opening credit reads diretta da Frank Merle, literally "directed by Frank Merle." Pupilo actually gave directiorial credit to producer Francesco Merli under his anglicized pseudonym.
Even in its stilted American version, the film is atmospheric and creepy. Sam Raimi must have taken note, as many scenes in The Evil Dead are obviously influenced by it (waking the dead by listening to an old recording, subjective shots of undead attackers, etc). One grisly death by acid seems to have been remembered/homaged by Lucio Fulci in the The Beyond, as well.