I read the main story and some, but not all of the short stories. My review will concentrate on the title story. 
 "I Am Legend" is the story that practically spawned the modern zombie (and partially the modern vampire) genre. There have been two movie adaptations, but the first followed the story loosely, the new one just picked the title and names. 
 The story follows the life of a man living alone in a world, where some infection turned people into vampires and zombies. He moves freely during the PA style city and retreats into his fortified home for the night. The story is more about his way of life and struggle to stay both alive and sane in his solitude. It's also about the value of life and struggle between species. 
 The story is written in a style fitting it's time. Do not expect a modern, quick paced, action packed story. There are many details about the infection as he investigates, not just some T-virus that wreaks havoc at every turn. 
 I could set my mind for the seventies when the story took place and enjoyed the story. It was realistic and enjoyable at the same time. The MC was an everyday practical man, not a superhero and made some decent progress. 
 The other short stories did not manage to grab my attention though. They were a mixture of horror short stories and gags. They were more like good high-school short story home-works.