While trying to weave a believable story the author added a whole bunch of historical figures some of which were completely redundant (Erzsebet). I will not even go to all the little weird historical "info" the author shoved into the story (rather than "woven"), such as Dee's introduction to Coffee and to Tea. I wont dare to ask if the author really believes that a man who worked in Queen Elizabeth's palace for many years was not familiar at all with these drinks...
Both the character of Dee and of Rabbi Loew were described in a very unreliable manner. Does the author truly believe that Rabbi Loew, a genius of his time, spoke only German, Czech and Hebrew? In Goldstein's world the Maharal (as Loew is commonly known) does not speak nor understand Latin and his scholarly knowledge is quite limited even though the historical figure was a renaissance man. Dee on the other hand looses complete contact with his historical figure, as he is portrayed almost as a Harry Potter minus the wand, striding about with incantations for opening doors and breaking windows.
Instead of feeling drawn into an authentic world of the Occult and complicated ceremonial magic one witnesses Dee's Harry-Potter-like incantations, which really ruin any chance of taking the book seriously. Loew too talks about magic as if it is something completely ordinary without any kind of reference to the problems arising in Jewish culture around these issues. Loew's magic is considered Kabbalah, but what about Dee's? How can Loew wander around with his spell casting Harry-Potter friend without any referral to the source of his powers? When Loew does speak of magic, as in the last scene in which he describes the surge of magic around the emperor, he does so as if he is a Dungeons & Dragons character and not like he is any type of historical or even fictitious Rabbi. In one scene Dee actually offers to teach Loew a certain incantation (?!).
Adding the Golem to the story wasn't really necessary, but even if the author decides otherwise I'd expect her to research enough to know that the Golem, as donated by his very name in Hebrew, *cannot* speak. All of the legends, regarding the Maharal's artificial man, talk of his inability to talk as his trademark. Indeed the book mentions that the Golem has the soul of an animal... this is exactly why he is not supposed to speak according to the inner logic of the story.
The novel's ending and "grand finale", is the point when we find out the identity of the 36th righteous man (I wont go into what the author did to this Jewish Legend), This "finale" is extremely predictable, which is annoying cause one expects some sort of surprise after reading through this Mambo-Jumbo and gets none.
Last but not least, the book skims over months at a time with one sentence, a book such as the Bible can afford being this brief, a novel such as this cannot. It has to give some description that will make the passage of events this quickly believable. Many of the descriptions are lacking and almost none of the characters feel rounded.
Summary: The book feels like a sketch, as other reviewers wrote. The characters are unbelievable even for a fantasy novel. When one writes a fantastic novel and chooses to do so basing it roughly on historical figures, one has to research to make the story succeed. I found that the history was not remotely realistic and the fantasy also failed to take off because of the supposed historical scenery.
Stretching the truth is ok in such as book and I really didn't care about magic playing an active part in the story (heck that's the genres whole point) but why make it so ridiculous. Harry Potter is readable because it doesn't take itself seriously and it isn't set in an historical environment, this book makes too many mistakes in my opinion.