Yeah, I saw this (er, BEYOND THE DOOR; there's so many films under discussion here now) for the first time many years back on VHS. I was immediately struck by how oddly it began; iirc, it began with the devil narrating the action of a pre-credits sequence. Everything from there on is so wonderfully bizarre -- from the San Francisco exteriors (which clash with everything else about the film) to the creepy frame holds in the editing during one of the possession scenes.
And yes, the music is great. Does anybody remember the camera angle from the descending elevator -- it was a shot of the husband walking towards the camera in a concrete courtyard? I love the funky bit of music there. When I first heard it, I ran to the closet, dug out my gee-tar, quickly learned the notes and starting playing along with it.
Btw, Mark Goldblatt (the editor of T2, the original TERMINATOR, RAMBO 2, X-MEN 3, STARSHIP TROOPERS, etc etc etc) is a huge fan of this film.