I have to say, I've been seeing a lot of these films for the first time, and this film has been one of my favorite discoveries.
Martin looks very young, probably a teenager, but he's not. He tells us he's 84 years old, and that he needs blood. We watch him, in the first few minutes of the film, drug a woman, rape her while she's unconscious, cut her wrist with a razor blade (leaving a few more blades and an open bottle of pills to make it look like she committed suicide), and drink her blood. He repeatedly protests that he doesn't want to hurt anyone; he just needs blood, and he tells us he's always very careful, which is why he's been able to live so long without being caught.
He goes to stay with his uncle, a superstitious old man who is aware of Martin's "condition" and is determined to destroy this Nosferatu, hopefully saving his soul before he has to do so. He hangs crucifixes and garlic around the house, but they have no effect on Martin, who tells his uncle again and again that "there's no magic."
There are fantasy sequences in the film, where Martin and/or the uncle conjure more traditional images of vampirism. The fangs, the cape, the seductions, the stakes -- even an old-fashioned mob with torches. These serve as a kind of send-up of the classic vampire lore and make the film just as much a parody of many of our favorite films of the sub-genre as a genuine entry in the sub-genre itself. The film is also peppered with calls Martin makes to a radio station, calling himself "The Count" and - under the cloak of anonymity - telling everyone what his life is like as a vampire and how different it is from the movies.
The best part about this film is that it may, in fact, not be a vampire film at all. Is Martin really a vampire? Or is he merely a deluded psychopath? He certainly doesn't show any of the traditional signs of vampirism - no aversion to sunlight or garlic or crosses, no above-average strength (he really struggles to overpower the woman in the first scene), and he even eats regular food. Indeed, the only signs we have that would confirm he's really a vampire are that he drinks blood and that he claims to be much older than he looks. This ambiguity makes for an ironic and pretty brilliant ending, and one that fits well with the rest of Romero's works.
Fun fact: Special effects goremeister Tom Savini has an acting role in this, and also did the effects, marking the first collaboration of many between Savini and Romero.
This is a great little film, definitely one of Romero's best.