Really puzzles me already taking into account when it was brought into play.
It really is no different to any other revealed faith. People either accept it because it is part of their personal reality due to their upbringing, family and social connections or they are converts. Unlike much of the bible, I understand the historical evidence is rather scant. Mormonism is a very American religion - one of their arguments appeals directly to people who live on that continent - that Messiah couldn't leave the sheep that were "not of this fold" untended, so as the story goes, he visited the Americas centuries ago. Sounds nice, I guess - but one could be forgiven for asking why he didn't visit Africa, Australia, South America etc - leaving behind sacred writings on plates for Joseph Smith types all of the world to find.
In Mormonism one gets a chance to be their own "god" of their own universe, which I guess adds to the appeal.
I've read a good deal of the BOM, Joseph Smith took many bible passages and put them in there. If I remember correctly, in the King James old English to boot.