The first 40 or so pages of this book really encapsulate a lot of what is wrong with the series overall: Oberon faces an unstoppable monster, reputed to have destroyed the armies of Chaos in a bygone era. Then he tries something he's never done before and succeeds where all others have failed. In the process he accidentally rewrites part of the universe, bringing Betancourt's vision of Amber an inch closer to resembling Zelazny's, but stopping before really accomplishing much. This part is also, thankfully, the only significant appearance of Betancourt's "fey."
Following this over-the-top opening, the book meanders for 150 pages. Oberon wanders between the two main storylines. The first involves betrothal negotiations with a woman that Oberon finds physically repulsive. The other is his visits to the newly arrived city beneath the sea, usually under the magical compulsion of the ruler there, Queen Moins. The action picks up a bit towards the end when Oberon manages to beat the greatest swordsman among Dworkin's children ("Wait, I thought Locke was the greatest...") and uses shapeshifting to disguise himself as King Swayvil ("But... I thought that Oberon's only ever seen Swayvil in dreams... and only as a dragon...") on a daring mission! And then he wraps things up with an out of the blue, over the top cliff-hanger. There are also a few bizarre plot twists in there, but I don't want to spoil them.
I will say that there were a few parts of the book that I genuinely enjoyed. Oberon-as-rake was well carried off. Regardless of other complaints I may have, Oberon's tendency to have his head turned by any pretty thing that crossed his path did earn a smirk out of me and I was more capable of seeing the future Oberon in those moments. And I enjoyed the big sword fight at the end, even if it was another illustration of "Gee, can nothing stop the might of Oberon?!" There were also a handful of cosmological/metaphysical points where I had to admit, "You know, I never thought of it that way."
Otherwise, I found the book lackluster. The dialogue had a lot of awkward moments, with characters over-reacting over a few lines of conversation, or even saying things that didn't jibe with earlier comments. When he's not accomplishing the otherwise impossible, Oberon is continues to be bumbling, short tempered and petulant. Betancourt had noted on one bulletin board that this book had been a rush job, and it shows.
But the biggest misfortune this book faces is this: It's not Amber. Literally. This is our first real, solid look at Oberon's new kingdom. This is Betancourt's chance to bring us into Amber, highlighting geographical points that Amber fans would instantly recognize. But he doesn't. There is no Mount Kolvir with the city of Amber perched on the side of it. Instead, Castle Amber is on top of a hill, with the city spread around it. The city of Amber is longer a port town, and the sea can only be seen in the distance from a tall tower. Places like the Valley of Garnath and the forest of Arden, if they even exist in this universe, go unnamed.
The previous book, "To Rule in Amber" gave us some warning of what was to come, but this book hammers it in. Even with Oberon accidentally rewriting the universe, only two things have changed: There's now a Pattern in the basement of the castle and there's an underwater city. Not Rebma, mind you, but "Caer Beatha." (As best I can tell, this name comes from someone's Amber Diceless campaign...) And that is all the similarity that seems to exist between Zelazny's Amber and Betancourt's.
This doesn't even include the scads of teasers Roger had left regarding the origins of the Amber universe and some of the artifacts. But given the example given by the original trilogy, readers shouldn't be surprised. Overall this book is mediocre as a fantasy novel, and awful in terms of describing the world of Roger Zelazny's Amber.