I recently just heard of this 70's cult-classic, and some were trying to compare it to or put it in the same realm as the 1973 masterpiece "The Exorcist." Let's be honest here...the ONLY thing that "The Possession of Joel Delaney" and "The Exorcist" have in common is that both do deal with the subject of possession. Other than that "Possession of Joel" does not even come close to an ink-ling of being in the same realm as "The Exorcist."
However, this 70's horror flick is pretty good for low-budget and the topic it deals with. There are plenty of bizarre and freaky moments, and the slow mental collapse/possession of 'Joel' was amazingly portrayed by a very young Perry King! Shirley MacLaine also gives a very excellent performance as the somewhat weird and mentally troubled 'Norah'.
But, the actor I had the most respect for, and thought truly had to go through a humiliating/horrifying experience, and handled it professionally (especially at his young age at the time) was David Elliot. He was the young 13 year old son of MacLaine and had to strip naked (exposing himself entirely) after the possessed Joel forced him to dance naked around the house to terrify him. That had to be embarrassing and I'm surprised they allowed it...but he handled the situation and that scene like a pro. This scene is also somewhat shocking and makes this film remembered among horror movie fans.
Overall...again don't expect "The Exorcist", but it is frightening and the character development, filming locations, etc... are excellent! This is a must have for horror fans/collectors!