Muhammad: Prophet of God, by Daniel Peterson
This has been an unofficial TBR title for a while now. It's a scholarly biography of Muhammad written for the layperson--the author is a professor of Islamic and Arabic studies, it's a fairly short book (less than 200 pages), it's very clearly written, and it has plenty of footnotes.
Everything that is known about the details of Muhammad's life is here, and a good bit about the early beginnings of Islam. Peterson also includes some information about disagreements on various issues and his opinions on them, where relevant. The best thing about it is how very readable it is; there's no jargon, it's all clearly set out in nice prose, and it's just a pleasure to read.
I enjoyed it, it was very informative and respectful without polemics either way, and it was a good solid treatment without becoming exhaustive.