I've read at least two articles authored by historians that thought this book was full of factual errors and misunderstandings. One of them had studied Eichmann's life and correspondance, and found that he was far from the character that Hannah Arendt depicted. IIRC, the other article tried to explain her bias; I remember she hated Jerusalem and despised most people she met in Israel.
It may be good read, but don't expect the book to be fair or truthful.