I rate this a five in spite of some legitimate reservations, too well expressed by too many people to bear repeating here.
The things I liked:
1. Brilliant writing style. Incisive, funny, powerful. (His followup to this book, a 94 page tract called "Letter to a Christian Nation" displays this skill to even better advantage.)
2. Sam's recommended actions for the reader. Religion generally gets a free pass to make unsubstantiated truth claims. Stop allowing that. Start questioning, and pushing back publicly.
3. Who SAYS "Faith" is a virtue Again, an unsubstantiated assertion that deserves some pushback.
4. Analogies: I love that Harris comes up with some new thinking in the atheist arena. Too many authors are trotting out Bertrand Russell gems, and as good as they may be, they're 90-some-odd years old. The best, IMHO, is when Sam asks the reader to distinguish between comforting religious truth claims and his (hypothetical) claim that he believes there is a diamond buried in his back yard, the size of a refrigerator, and that it gives him great comfort to know that at some point in his life he can choose to be very rich.
In the current climate, one would get him branded insane, and the other would get him branded a man of strong faith. Bollocks to both, I say.
5. Moderation supports extremism. It's not appealing, and those in the middle are looking for compromise and wiggle room, but it really DOES come down to some black and white, true/false determinations. Choosing to be moderate, as Sam says, betrays both one's faith and reason.
This may be the hardest pill for Sam to get readers to swallow, because it requires the most sacrifice of one's own foundations (if one is moderately religious, that is.) This proposition simultaneously asks the moderate believer to abandon thoughts that they have held to be sacrosanct from their youth, and then as a consequence, "disaffiliate" themselves from a tribe with which they have strong identification. (tribe/religion... whatever.)
A compelling read that I thoroughly enjoyed, and which I love to imagine moderates reading and squirming through all the uncomfortable passages. Which is precisely Sam's overall goal... to remove the "comfortability" of lolling around in one's unjustifiable faith propositions, at the expense of the rest of humanity.