This is the hardcover 3-in-1 book club edition of the three novels that make up the Eschaton series. The Other End of Time; The Siege of Eternity & The Far Shore of Time.
Frederik George Pohl, Jr. was an American science fiction writer, editor and fan, with a career spanning over seventy years. From about 1959 until 1969, Pohl edited Galaxy magazine and its sister magazine IF winning the Hugo for IF three years in a row. His writing also won him three Hugos and multiple Nebula Awards. He became a Nebula Grand Master in 1993.
I actually read the books separately, after waiting until I had the entire sequence.
Pohl is an amazing storyteller, and throws in a few plot twists every now and then. One reviewer called this trilogy "the thinking man's Independence Day", and there are a few commonalities between this and that movie.
The only complaint that I have is that the ending didn't seem definite; yes, the bad guys (?) were defeated - for now. I couldn't help but think that Pohl was considering revisiting the trilogy with a fourth (or maybe fifth) book.
I really enjoyed this book. Having all three novels together was a definite plus. Pohl's creativity and manner of using scientific knowledge in a "user-friendly" way gave the plot depth. I'd read this book again-and probably will, before too long!