Probably in the 3.5 Stars range but rounded down for not living up to its reputation as a SF classic.
Eon has an amazing premise: a strange object shows up that appears to be a hollowed out asteroid in early 21st century. Humans visit the asteroid and discover that it was actually created by humans 2 centuries in the future. But even though it has room to carry millions of people the object is devoid of inhabitants. And it carries a mind-bending secret that will change how we view the Universe and our understanding of space-time.
I knew all this going in, but what I did not know is that the story is told in the context of the Cold War with American, Russian and Chinese characters occupying the main parts of the action. So, The Stone (as the artifact becomes known) is a focal point for the national rivals as each (rightly) assumes that the technological advances that will result from whoever controls The Stone will be dispositive in determining who controls The Earth. I actually like political intrigue and may have enjoyed the book more if the story focused more on that aspect.
However, about one-third of the way in we are introduced to the aliens who created (or just utilize?) the secret technological marvel details of which I am trying not to discuss in order to avoid spoilers. And from my perspective that's where the book goes off the rails. We eventually end up learning way more about the social and political dynamics of the alien culture than I cared to or was interested in. I suppose for some readers this may have been the highlight of the book but for me it was simply uninteresting.
What I did like was the main character of Patricia Luisa Vasquez, a 24-year-old mathematician (Fields medal winner!) who gets tapped by the White House Chief of Staff to join the team exploring The Stone and who becomes increasingly important to many other aspects of the story. I have to applaud Greg Bear for centering this book around a Latina scientist, especially since it was written at a time when issues of diversity and representation were not as prominent as they are now. That being said, there are still some problematic ways in which gender stereotypes infuse the story (particularly in the depiction of sexual relationships between the characters) that also lowered my appreciation for the book.
Overall, I would say Eon is a mildly interesting science fiction novel with an awesome premise that doesn't live up to its reputation as a SF classic, primarily due to somewhat dated characterizations and unfortunate plot choices.
Author: Greg Bear.
Paperback: 512 pages.
Date Published: October 15, 1991.
Date Read: January 3, 2018.
GOODREADS RATING: ★★★☆☆ (3.0/5.0).
OVERALL GRADE: B (3.0/4.0).