4.5 stars - it's an excellent, enjoyable and thoroughly interesting look at the mechanics (the 'how') of leaving a belief system. 4 stars + a bit more for being the first serious study of what some folks are going through and a nod to the effort required to track down many of the respondents, men and women who retain all the outward signs of piety with regard to clothing, family, beards/hijabs, and friends yet secretly do not believe.
These private respondents stand in contrast to others more public who have to then go on a counter-offensive when they are deemed as shallow people who simply want to drink and sleep around (but even ex-Muslims never eat bacon, which was a hilarious part of the book) and explain why they've left has little to do with weakness of character.
Appreciated how the author was clearly extremely well read on the issue of the complications of leaving tightly woven communities, and the literature he cites on this issue in general is fascinating. Most interesting to me was how nearly all the folks in the book were pretty content to ditch the theological contradictions without too much agonizing beyond the inevitable questions about what belief system does one adapt if they leave faith, and how different folks 'came out' to their parents or friends or community, with interesting parallels to gay literature from the 1980s and 90s and the burning desire to stop pretending to be something they aren't. Expected, but he addresses it with care. The weight of how others perceived you was of course the dominant theme.