I read this book as "homework" for the FACT reading group, but ended up not going to the discussion because I've been steamrolled by work. Regardless, here is my review.
To sum up my opinion, it's a good character study, but a bit lacking in originality, and certainly lacking in scientific credibility.
The story follows a guy who (believes he) is the last surviving human after the Earth has been overrun by vampires. A cover blurb says Matheson was a big influence to Stephen King, and I wonder if that was the reason this book gave me a continuous deja vu. Stephen King has dealt with apocalyptic scenarios in some of his books, as well as with supernatural horror, though I think he did a better job of these two genres.
I was intrigued not so much by a premise that the humankind has been wiped out by / transformed into vampires, as with the notion that you can make an entire novel out of the last survivor's experiences (a short novel, but still). If the protagonist is the only person left alive in the world, what is the book going to be about? Him living out his days and dying? That would hardly make an interesting story. Thus, to fill up those 171 pages, something unexpected has to happen. Was the protagonist wrong in his assumption that he was the last person on Earth? The story is in no rush to reveal it. As the story goes on, you start to wonder if you were wrong and this is really a book about a lonely guy living out his sad, meaningless existence in a world without a future. He starts out desperate and pathetic. He is devastated by the loss of his wife and daughter to the vampire plague, and even more so by the realization that he is doomed to be alone until the end of his life. Even so, he's focused on survival. Each day he swings between alcohol-fueled rage and a tenacious, clear-headed effort to do what he needs to do to make it through one more day. Matheson portrays the character's emotional state so vividly and movingly that not only I sympathized with the protagonist, but I also started to think, grudgingly, that even if nothing more happens to him, the book will still be interesting enough as a character study of the last survivor.
Then the story gets better still, as the guy overcomes his alcoholism and becomes determined to find a scientific explanation of the vampire plague. That was the part I could really identify with. His frustrations reminded me a lot of my days in graduate school, when I used to bang my head against particularly ornery projects, or even of my current bouts with writer's block, as I struggle to think my way out of plot dead ends.
Yet when he found an explanation, it was very disappointing -- to me, at least -- because it was so implausible. Even more implausible was that nobody found this answer before him. And he wasn't even a scientist by training! He was merely a smart guy who taught himself biology from textbooks. Even though the plague was fast and the humanity, including all "real" scientists, was gone in a matter of weeks, it's still not likely that the CDC and other experts did not have time to make the same discovery that this self-taught scientist eventually did. Science is not this book's strong suit. Also, the ending did not seem well thought out. Certain things happened for no good reason.
The rest of the stories in the book were even more Stephen King'ish in their spirit. Their dominant genre is supernatural horror. There isn't much science fiction in them. But the characters are vivid, and their situations resonated with me in ways that held my interest despite the fact that this isn't my genre.