"He was honored by fans with three Hugo awards and by colleagues with one Nebula award and was named the third Grand Master by the Science Fiction and Fantasy Writers of America (SFWA) in 1977." (Wikipedia)
This book contains three novels. I'll review each as I read through the entire book.
Time is the Simplest Thing: This was a rough read that I would give 1 star. It takes place in a future where there are normal people and paranormal (psychic) people. This is the story of one para who encounters an alien intelligence that takes over part of his mind. I won't spoil the story other than to say he decides to run and the rest of the book involves the chase.
Way Station: I've read this before which is why I picked up this collection. This is one of my personal favorites and it lived up to the re-read. It is the story of man who doesn't age because he is working a galactic way station on earth that nobody else realizes is there.
A Choice of Gods: This was another rough read. It is the story of an earth where just about all of the people have disappeared. The people that remain now live extremely long lives (5000 years). I wasn't really sure where this book was going and that was true even after I finished it.
Bottom line on this collection: Get a copy of Way Station and just read it.