Here's the thing. The whole Book of Mormon thing has no real historical evidence for it, as the Bible does (at least much of it), and the story of Joseph Smith and the belief in polygamy, etc,...just seem false.
But is there a presence with it?
Yes, and there is spirituality and many real Christians, I suspect.
But the best thing the Mormons have going for them is that for the most part, they live very godly, family oriented, dedicated lives, or it sure seems that way looking at the ones I have known, and for that fact alone, I give them the benefit of the doubt as to being real Christians.
I think the Book of Mormon, though, is probably a fantasy created by Joseph Smith, and there are some skeletons in the Mormon history closet.