There is some merit to the criticism about The Books of Jakob being a little boring (at least for a few pages).
The novel's plot revolves around Jakob Frank (1726-1791), by turns Jew, religious leader, Christian, Muslim and Messiah. "Frank"'s meaning being foreigner, Olga plays with another messiah's famous saying: "no one is a prophet in his own land" by turning it into "a prophet must be a foreigner. He must have come from another land, or, at the very least, have fallen from heaven".
After a promising start, the next few dozen pages are hard work (Olga does indeed show off her encyclopedic knowledge of Jewish lore), until Haya and Jakob get together. At that point you feel like you're in the hands of a master storyteller, you can see the smiling way every detail feels pregnant with meaning, foreboding, irony or allusion.
For example, Haya joins the men in her father's room to participate in their debates (Aya's mother sighs, "if only Aya had been born a man, she'd be the wisest of my children"). This surprises Jakob, who's not used to this kind of thing: "in Turkey and in Walachia women know their place and men know better than to mix with them, because their innate place inside the lowest world, the material world, seeds chaos among the spiritual world." And then, in the very next scene, Tokarczuk shows Jakob and Aya in bed, and subtly and metaphorically points out how Jakob's future is going to evolve:
"The first night, as their custom mandated, Haya laid down on Jakob's bed. Her body was delicate, maybe a little too lean, her legs long, her pubis rough. They should have coupled silently, without useless ceremonies, and yet, Jakob caressed tenderly and repeatedly the young woman's supple belly, and every time her belly button felt hot like fire. As for her, she gently grasped his member on her hands, with ease, in order to tenderly coax it, almost as if unawares. Haya asked him about the steps needed to convert into the Turkish religion, what took the place of baptism, if some preparations were needed, how much did it cost, if Jakob's wife also abandoned Ismael's side and if women's lives were easier there; did their conversion protect them really? Even from the Polish authorities?"... (Les Livres de Jakob, Editions Noir sur Blanc, 2018, chapter 15).