After reading half of "Under the Banner of Heaven", I decided that was enough for me.
It's not that Jon Krakauer a hack author... to the contrary, I enjoyed from him the books "Into Thin Air", "Into the Wild" and "Where Men Win Glory" (reviewed here).
The issue I had with "Under the Banner of Heaven" is how distasteful is was to read about true wackos who do something horrible and at the same time pervert religion (in this case the Mormon religion) by using it as the basis for their twisted actions.
I understand Krakauer's intent to explore the basis behind a heinous crime, but for myself as a reader, it's both not worth it and the connection isn't there. Not worth it from the perspective of there being little redeeming in reading about said crime (yes, I know the world not a shiny, happy place). As to the connection... while the actions perpetrated did come from people who were at one time devout Mormons, they were also kicked out of the church before committing their crime.
I did find interesting reading about where the Mormon religion came from and can see how it's views could be peculiar to someone not in the Faith, but it would seem patently unfair to hang the blame for this deranged behavior on the Church. Kakauer didn't seem to have this goal, but for me as a reader... if they're just wackos, then the background of the Church has to stand by itself apart from what turned these guys into said wackos.
Definitely not a poorly written book... just one about people I didn't care to read about.
To the subject of the author himself... pretty fascinating recent 60 Minutes piece (featuring commentary by Krakauer) on "Three Cups of Tea" author and Central Asia Institute charity founder, Greg Mortenson.