Disclosure: I received a free advance uncorrected proof of Zealot by Reza Aslan courtesy of Random House, via GoodReads First Reads.
Zealot is not so much as biographical account of "The Life and Times of Jesus of Nazareth", as it is billed in the subtitle, as it is an in-depth historical exploration of the political and cultural climate during which Jesus' ministry took place. As Aslan admits, there are few sources that reveal much factual certainty about the historical Jesus. Much of the biographical detail, such as whether Jesus' mother was unmarried when he was born, is purely speculative from minute historical or Biblical clues. Nevertheless, Aslan does an admirable job of illuminating the background of Jesus' ministry, his possible sources of inspiration, and why people may have responded to him in the ways that they did in that historical context. Aslan also clears up a number of common misinterpretations of Gospel passages, such as the probable original meaning of references to Jesus as the Son of God that were later reread to establish the basis for Jesus' divinity. The final chapters of Zealot are concerned with the early church in the decades following Jesus' death, and although they are interesting in their own right and shed some further light on how Jesus' mission was either carried on or distorted by his followers, these sections probably belong in a separate work about early Christianity, as they do not adhere strictly to the topic of Jesus or his lifetime.
Not strictly a layman's text, Zealot requires a basic understanding of academic scripture study, ancient history, and theological terminology, as it might otherwise be a slightly difficult read. Readers who are interested in a more introductory work on the search for the historical Jesus would be best advised to start elsewhere, as this is more a scholarly than a popular work.