The book is well-researched. I have to give the author that, and I have to applaud the amount of time and effort that went into making the events this book portrays historically accurate. At least, to an extent. Her language use is not anachronistic, despite jumping between several hundred years, and she tells us vividly what happened in each war, each conflict.
I have two main grievances with this work. The first, is that I find that there is no major goal for Helen, the deuteragonist, of all people. It feels like she's just there to give Elias a love interest (moreover, the romance felt forced), and that she plays absolutely no part in the plot at all. Sure, she studies Huntington's Disease, and serves to give the readers some kind of tutorial for the scientific concept behind it. However, beyond that, she seems... extra. The plot could have been carried out with just both the Lusignan family and Elias alone, and there was no need for Helen at all. In my opinion, the story would probably have been even better without her, and if modern-Elias' main goal is to protect Mystras.
And the second is that I don't find myself bonding well with the characters. The author jumps from scene to scene, from POV to POV, so quickly, every other scene. There is no time for me to really feel for them, feel with them, as they go through the events. I find myself jumping from Elias, to Helen, to minor characters like Charlotte Lusignan, and... other people that I cannot remember. In any case, it was difficult for me to identify with the characters, and I felt like I was just going through the motions like I'm reading a history textbook, or a biography (or an autobiography, in Elias' case).
In retrospect, I struggled to finish this. I forced myself to read 100 pages a day (on Libby on my phone). I think, however, this book would suit people who are big Greek history buffs. I wouldn't even recommend this to people who like romance, because the romance is only a sprinkle in the grand scheme of things.