As another poster pointed out, Krakauer's great book 'Under the Banner of Heaven,' is an excellent source, not just to understand the Mormon thing, but religion in general. I'm sort of spoiling it here, but Krakauer uses the LDS Church as a case study in the way religions are actually invented because the LDS was invented in a time and place where records were kept and there were journalists, historians, etc.
Anybody on this forum, including the lurkers, who have not read this book need to get off their duffs and read it. Actually, I guess you get on your duff when you do the actual reading.
He gets to the heart of the whole deal with the Abrahamic religions. Hint: all the Abrahamic religions are batshit crazy! JWVH inspires murder and worse! The Bible could have been written by Richard Matheson!
IMO, the 'moderate' or 'mainstream' Xians don't call out Mormon or Jehovah's Witness or 7th Day Adventist silliness much is because they secretly know they are all standing in glass houses.
As another poster pointed out, if a person were raised a religion free environment, Mormonism wouldn't look much different from any of the other Abrahamic religions.
Anecdotally, most of the Mormons I've met are nice. They do cover up their own problems, there's a lot of secret alcoholism and family abuse, but they have these 'social services' via their temples...to the outsider, it looks like 'oh how nice, they are taking care of each other!' and maybe that's part of it...but another part is they like to keep outsiders away. Therefore the elders cover it up and don't report to the law when there is rape or child molesting or stuff of that magnitude.