This author has written at least one previous novel, and a collection of short stories, about the Byzantine Empire, focusing on the late period, after the year 1000. This is certainly the best so far, and the Author's Note seems to say there is, or soon will be, another in the series. I'm looking forward to reading that one too.
The Byzantine Empire is poorly represented in historical fiction, even though it doesn't seem particularly unsuitable for such treatment. Like, say, the Tudor period in English history, there are a number of contemporary accounts accessible to the historian (I've read several of the ones the author lists in the historical note, in translation, and the dialect of Greek they're written in is not especially difficult to learn for the serious scholar). Any historical fiction has the challenge of fitting your plot into the events of history. If you're writing about, say, the Trojan War, or Alexander the Great, you have little in the way of sources and have to fill in the gaps. Then, the reader could come away with an idea of history that's distorted. When I read Mary Renault's novels about Alexander the Great, her Alexander became the real one for me, even though recent scholarship says that's not the reality.
You have very little of that problem with this novel. It hews so close to the history that you can actually learn the history from the novel (usually a dangerous thing to do). But, that's a weakness as well as a strength -- the history is extremely complicated with lots of players -- or should I say characters? doing things that must be included or the reader won't understand what's happening. It's another problem that the Byzantine aristocracy of the period had complex relationships of kinship, and re-used names very often so that there are many Annas, Basils, Romanus's, Constantines, and Johns. While some of them have last names, the Byzantines were just beginning to adopt surnames in the period and the concepts we have of naming don't seem to be followed all the time. However, given that, the names aren't hard to pronounce or spell, nowhere near as bad as those in Russian novels. So, having addressed the two ambiguous features of the book, let me pass to those that are unqualified strengths.
The main character, Anna Dallassena, is fully realized and extremely easy to identify with. She's a member of the military aristocracy, daughter of a general, and pleased to be betrothed to a high ranking commander when still a teenager. She loves her husband had has a number of children with him, and she's a devoted mother as well. She's on the fringe of the ruling class of the Empire, and we get to see that's a two edged sword because when your family is implicated in political opposition to the Emperor, you risk being sent to a monastery or convent. (If you're a man, you could even be put to death or have your eyes put out). The author ties in the personalities of key players in at least 3 families that are competing to take the position of Emperor. The reader needs to consciously recognize that this isn't a Western monarchy where the king rules by divine right, with primogeniture determining the succession, it's an empire where people have titles but they are not hereditary and therefore there is an intense competition for them. The top one, that of "King and Autocrat" (Basileus kai Autokrator), is the highest goal for the social climber.
In my student days, I majored in archaeology and took a course in Byzantine history, over 40 years ago but I still recognize a lot of the names. My professor stated in the first lectures that the Empire could be understood as a power struggle between three elements: the Imperial bureaucracy (administered by slaves under the early emperors, and later mainly by a class of eunuchs), the Army, and the Church, which was the ancestor of today's Greek Orthodox Church. The Army had been partially feudalized after the Dark Ages with some of the cost of supporting it being localized in the form of "Themes". Therefore, there were both Imperial soldiers paid by the Crown and thematic units paid by the landowners in regions where they were stationed. But, promotion was by merit and couldn't be inherited. The author clearly knows all this but doesn't get into it more than she has to, probably a smart decision because it would make the novel more complex...durst I say Byzantine? than it is. We get to learn quite a lot of Greek terms. The aristocrats are "dynatoi," from the same root as dynamite and dynamic, meaning the powerful. Women wear a headdress called a maphorion. We learn about the religious festivals, wedding and funeral customs; there's a state church centered in the magnificent cathedral of Haghia Sophia, which still stands in the ancient city. The Empire becomes familiar without the text ever seeming didactic or tedious. It's a long tale but moves very fast, with lot of emotional ups and downs that keep you on the edge of your seat. The ending made me cry.
There are elements in the Empire's decadence that will seem similar to events of recent history. The Turks are attacking at every opportunity, sacking cities and selling the inhabitants into slavery. There's a problem keeping the emperors from spending the treasury into poverty and borrowing from Italian bankers to cover the deficits. No one can say no to an emperor. While there's a theoretical separation of powers in that there's a Senate, which most of the dynatoi belong to, it has little real power. All that is reality from the time.
This is a superb book that deserves your attention. It will give you a painless, entertaining exposure to a little known period of history.