Disclaimer: The version of the film that I watched was included in a compilation package called 'Horror - Do Not Watch Alone 15 films' by TGG Direct. (This is nearly the same edition as Horror - Do Not Watch Alone (20 Classic Horror Films) by the same company.) As such, I cannot comment on the quality of this product - my review is concerned with the entertainment value of the film only.
There are several elements of this 1973 film that work well and should appeal to viewers with different tastes; however, taken together, I suspect that these elements don't always compliment each other. Those who might appreciate some aspects may not care for others, which makes the film weaker as a whole. Unfortunately, the way that this film is marketed (in individual packages as well as compilations such as the one I have), it is very likely to turn off those who might enjoy it most, and mislead those who would probably like it least into buying it. You must stretch the definition to its very breaking point in order to call this a horror movie - it barely even works as a thriller. More than anything, it is a police procedural, with Christopher Plummer's detective investigating the death of a heroin-addicted call girl played by Karen Black.
One of the benefits of these compilation discs is that I usually have little idea of what the movie is going to be about before I watch - it takes me be surprise, so to speak. Without any expectations, I enjoyed 'The Pyx', even as I could see its weaknesses. In a very excellent opening, the credits appear over scenes shot from the interior of a Montreal cabdriver looking out at the city. At the end of the credits, in the corner of the camera lens almost off screen, we see a body falling from one of the downtown high-rises. This is so underplayed as to almost be shocking. Regardless, the police are quickly called, and thus begins the investigation. As the film continues, we are treated to flashbacks from the point of view of the victim Karen Black interspersed with the investigation into her death.
The film is atmospheric and slow. Director Harvey Hart seems to be going for an accumulated creepiness, though I think the flashback segments interrupt the narrative flow too much to ever establish that kind of mood. What's left is the mystery of exactly what happened to Karen Black's character in her last few hours, although since we do know the eventual results, it does seem a bit academic. Since every other official blurb for this film lets on that there is involvement with a devil cult, it seems like no spoiler to mention it here, though that _is_ the crux of the mystery. Except there is no overt supernatural element -- and using that particular element to make it sound like a horror film is likely to only disappoint people.
With no expectations, and with an attitude that is generally favorable toward 70's cinema (at least to the point of being indulgent toward its many faults), I admit I rather liked this film. Christopher Plummer, Karen Black, and the supporting cast were all in top form here, and even though the film took its time, I never got bored with it. Those who detest slow, mood-building films should probably avoid 'The Pyx', as well as those who have an inherent dislike toward older films, though patient mystery fans should enjoy it.
Of course, there were some points that detracted from it too -- the most, to my mind, was the ending, where the flashbacks met up with the starting point of the story. So much time had been invested to get us to that point that the payoff seemed rushed and unsatisfactory. Also, the choice of having Ms. Black sing on the soundtrack will appeal to some and not others -- I personally like the songs, but the style dates the film. All together, the positives outweigh the negatives, but only by a slim margin. 3 1/2 stars.
From other reviewers and studio information provided by Amazon, its very difficult to tell if _any_ of the current packages of this film are worth investing in. The version I watched was satisfactory for the price I paid (about 50¢ after averaging), though it had several defects - most notably it was very dark. I also watched it on a smaller screen, and I would imagine large, hi-def screens will augment other problems. Those interested in the film may want to wait until a quality imprint releases it, or resign themselves to the defects on the lower-priced horror collections that currently offer it.