Martin Marty is a retired professor of the History of Religion at the Divinity School at the University of Chicago and retired pastor in the Evangelical Lutheran Church in America, a liberal or mainstream church denomination. He wrote this brief biography in the Penguin Lives Series, which is aimed at a general audience, rather than to scholars or Christian believers per se. Nonetheless, the book is a useful starting point for readers interested in Martin Luther and the Reformation.
Luther emerges as the product of the late Middle Ages, German culture, and the academy. Luther grew up the son of middle class family, but rejected his father's insistence on a career in the law for the life of a Catholic monk, which caused decades of conflict.
Luther taught at a local university and served in a monastery. In this life, he seems to have been haunted by the fear that he did not know how to please God and would not be able to do so. If one were writing from an expressly evangelical Protestant point of view, one might suggest that the Holy Spirit used gnawing question to drive Luther, a keen student of the biblical languages, to uncover the gospel of grace hidden behind the standard works-based salvation of the Catholic church of his era.
Eventually, Luther left the monastery, took up the work of a pastor, then married and had children with a wife who had left the life of a nun. They seem to have had a fine and contented marriage, even as Luther came under condemnation from the Pope and in danger from capture by pro-Catholic German princes. (Keep in mind, Germany was not yet a nation state at this point).
Over the course of the book, Marty traces Luther's theological development, his writing and teaching, his martial and family life, and his conflict with the Catholic Church and Catholic German rulers. He does not shy away from Luther's apparent antisemitism (something endemic to German and European culture of of the era) nor his highly questionable religious advice of certain political leaders.
All in all, I would be surprised if academics of the relevant subjects would gain much here, but I do think that the interested reading public will gain much for the investment of a close read of this short, well-written, and very informed biography of Martin Luther.