Youtube has it online divided into sections. part 1:
part 2, part 3, part 4, part 5, part 6, part 7, part 8, part 9
The entire film is here (as of 10/25/2011):
Moria declares it "a genre classic". The New York Times closes its review by saying, "As a setting for unadulterated horror, it will leave its audiences yearning for that quiet, sunny little motel in "Psycho."" Images Journal discusses how this film shows the "expressive power of [Bava's] directoral style". 1000 Misspent Hours says,
Whatever you think of Bava’s work as a whole (and he’s one of those directors whom people seem either to love or to hate), I just can’t imagine anyone finding much to complain about in this movie.
Senses of Cinema says,
Beginning in the late 1960s, Bava's The Mask of Satan/Black Sunday has often been cited by film critics and historians as an example of an influential and effective horror film of lasting artistic value.
10/31/2009: Barbara Steele's scream in this film is examined by Arbogast on film.