A very odd vampire movie, of sorts, from Romero. The story walks a long, lazy line down the mystery of "is Martin a vampire or just crazy?" I thought the answer was made very clear early on, but I still liked that an effort was made to keep one guessing.
So, what is this about? We follow Martin, a shy boy (I say "boy," however he looks like he's in his late thirties), while he stays with his... cousin - cousin?! Who are we kidding?! This guy is his grandfather or at least a very old uncle. Anyway, Martin stays with this guy, and he is ultra superstitious (read: insane) and believes Martin is a vampire.
The story is told in an interesting way that reminded me a lot of _Henry: Portrait of a Serial Killer_ (1986), which may have drawn inspiration from this. What I mean is, this is a character study where we follow the killer in his day-to-day life. An even more modern example of this would be _American Psycho_ (2000).
The movie is a slow burn, and the ending was unsatisfying, but it had enough good moments to not be a complete waste.
Definitely not a recommendation for fans of vampire movies, but if you like slow, eerie slasher movies, this will probably work for you. Basically, this is like following Ted Bundy or Jeffrey Dahmer, only with a twist of "are they human or a supernatural monster?"
I think this would have made a great book, but as a film, it drags, and not enough time is available to bring the story to life in the correct way.
Worth at least one watch if you are a fan of '70s horror.

Post script: There is a scene where chickens are killed. It added nothing to the scene, and was purely added for shock value. Disappointed in Romero for having a moment like this in his movie. Chickens - along with the other beings we needlessly kill - are sentient, feel pain, and don't want to die. Nothing gives us the right to take away their only life. In the same way a character like Martin would be viewed as the villain for murdering humans, so are carnists, for murdering non-human animals, for what amounts to pleasure.
If you want to justify an action with "it gives me pleasure," well, what cannot be justified with that?