So yes. Krakauer's book. If anything it sort of pulled punches--despite the horrors it details about the Lafferty murders and the FLDS/UEP/whateverthefucktheyrecallingthemselves, I'm not quite sure Krakauer ties Mormon-based fundamentalism strongly enough to its forefathers and cousins in the mainstream LDS church. No matter what the church proper says, the ties are there. Quite frankly, I have more respect for nutbar fundamentalists with their six wives and forty children than I have for Mormons who preach in Sunday school that plural marriage will be waiting in the celestial kingdom, but those inbred hicks down in Colorado City are perverting Christ's kingdom! If you're going to preach something, you might as well practice it. This is not to say that the LDs church necessarily breeds murderers. It DOES breed--or encourage--a mindset which marginalizes anything "other", represses women and minorities, and does not tolerate doubt or questioning authority.
I have heard people say that they found Under the Banner of Heaven difficult to follow. Its narration bounces between a brief history of the LDS church (with focus on Joseph Smith and polygamy) and the events leading up to and fall-out of the murders of Brenda and Erica Lafferty by two of Brenda's brothers-in-law. I suppose for those not familiar with the church, who are reading the book as an informative text, the structure is a little confusing. For me, it made perfect sense. I could see where Krakauer was going with things before reaching his weaving-together of points or figures which would likely have seemed disparate to a reader unfamiliar with church history. Presumably the church leaders are unhappy with this (I mean, they're unhappy with the book in general; a big rebuttal/bitchfest was written before the book was even on shelves; in the edition I have Krakauer responds to the complaints in an afterword. Admittedly there were a few editorial or historical errors in the first edition, which are corrected, but most of the problems the church officials had with the book were differences of opinion)--the idea that anyone familiar with LDS history, whether a current member, disaffected member, a history buff, or jack Mormon, will be like OH YEAH I KNOW EXACTLY WHERE THIS GUY'S GOING when Krakauer's on a bent about peep stones or the Dream Mine or Section 132 or whatnot...is disturbing to the people who run things. It's actually kind of funny that the church authorities got so bent out of shape; this book doesn't really tell anything that wasn't already available in other books and online. The only shiny new thing is that Krakauer is not LDS and is a popular author, and so his book has had more attention from broad audiences than, say, the Tanners'.
(My that was a long and convoluted sentence!)
At any rate, I didn't find Under the Banner of Heaven difficult to follow or understand. I guess it's a bad sign that I felt like Krakauer was holding back. How warped is that? A book explicating the reasonably sordid history of the LDS church, a book that essentially blames that history for producing fundamentalists given to incest, illegal polygyny, and murder--and my reaction is, Meh. I don't know exactly why I'm underwhelmed by this book, but there it is. It is a pretty good introduction to mainstream and fundamentalist LDS groups, certainly.