Yes, Marvel is only releasing this now to tie in with the new mini-series by Neil Gaiman and John Romita Jr. Yes, Marvel's shoddy treatment of Jack Kirby - especially around the time of this series - has been well documented. Yes, Marvel dictated editorial changes including Marvel Universe guest stars and Kirby was forced to capitulate, albeit in his own unique way.
Still, having all 19 issues (plus the annual) between two covers is an awesome thing. Kirby was always a creator ahead of his time; his initial plan for the Fourth World saga at DC was to eventually have the series collected into bound volumes, something that didn't happen during his lifetime but which has come to pass since his death.
Some fans consider The Eternals to be Kirby Lite, a watering down of his creative powers after the commercial disappointment of the New Gods. But in some ways, I prefer The Eternals - the art is even more cosmic, and the storyline stretching to the dawn of time induces as much awe.
For those bellyaching about this book, I don't see the cause for complaints. It's beautiful, with vibrant colors, all the original covers, a wonderful introduction by Kirby collaborator Mike Royer, and Jack's original text pages reprinted at the end. While I agree the binding makes it difficult (but not impossible) to read dialogue or narration near the spine, that is a minor complaint. (It also cost the book one star in my rating, but only because I couldn't take away half a star, instead.)
It may have taken decades, but Kirby's belief in the after-market worth of comic books - i.e., the bound collection, sold in bookstores - has come to pass. This collection and others like it are his vindication from short-sighted editors and fans of the 1970s who turned up their noses at Kirby's work. Even though editorial mandates forced changes the artist was not happy with, the talent and sheer Kirby moxxy shine through on each and every page.
Read the new Gaiman series - it is a wonderful homage to the King's talent. Then go back and see how it came to pass originally. This is cosmic stuff, and it jumps right off the page, just like it did when originally published.
If you are a casual Kirby fan, I recommend this book. If you are a hardcore fan, you already have it.