The Book of Mormon is a volume of holy scripture comparable to the Bible and is a record of God's dealings with His chosen people in the New World. The main purpose of the Book of Mormon is "to the convincing of Jew and Gentile that JESUS is the CHRIST, the ETERNAL GOD, manifesting himself unto all nations." (Book of Mormon Title Page) It was written by ancient American prophets for our day (Mormon 8:35) and is an American testament of the Lord Jesus Christ.
My favorite online apologist, Kerry Shirts (aka the Backyard Professor), has produced some new videos on the Book of Mormon 3 & 8 Witnesses and a refutation of critical charges of fraud or delusion on the part of the witnesses. Furthermore, the works of Richard L. Anderson, specifically his book Investigating the Book of Mormon Witnesses and his many articles on the Neal A. Maxwell Institute website are strongly recommended as further reading on this subject.