Throughout much of the Book of Mormon, the Lamanites are the designated "bad guys" and the Nephites the designated "good guys". The Lamanites would frequently launch invasions of the Nephite homeland, usually coinciding with periods when the Nephites failed to live up to the principles of the Gospel they were given. While the Lamanites would initially prevail, the Nephites would repent of their sins, call upon the Lord for assistance, and drive the Lamanites out of their land. But the fact is, the Lamanites did exhibit some positive characteristics from time to time.
Around 74 B.C., a large Lamanite army invaded the Nephite homeland once again. While the leader of the army, Zerahemnah, was a Lamanite, he had appointed subordinate leaders from the ranks of Nephite dissenters who had joined the Lamanites because they were of a more wicked and murderous disposition than the Lamanites; Zerahemnah wanted his army totally stoked up with hate. Initially the Lamanites prevailed, but the Nephites had appointed a brilliant 25-year-old military strategist named Moroni to command the Nephite forces. Eventually, the Nephites prevailed. As the Nephites were mopping up on the battlefield, Moroni encountered Zerahemnah, and extended to him the customary peace offer: Give up your weapons, make an oath that you will not attack us again, and we'll permit you to depart in peace. This had always worked in the past.
But Zerahemnah reacted differently this time; he was tired of the hypocrisy of Lamanite leaders constantly making peace oaths and then turning around and breaking them. From Alma 44:
8 And now it came to pass that when Zerahemnah had heard these sayings he came forth and delivered up his sword and his cimeter, and his bow into the hands of Moroni, and said unto him: Behold, here are our weapons of war; we will deliver them up unto you, but we will not suffer ourselves to take an oath unto you, which we know that we shall break, and also our children; but take our weapons of war, and suffer that we may depart into the wilderness; otherwise we will retain our swords, and we will perish or conquer.
9 Behold, we are not of your faith; we do not believe that it is God that has delivered us into your hands; but we believe that it is your cunning that has preserved you from our swords. Behold, it is your breastplates and your shields that have preserved you.
10 And now when Zerahemnah had made an end of speaking these words, Moroni returned the sword and the weapons of war, which he had received, unto Zerahemnah, saying: Behold, we will end the conflict.
Yes, Zerahemnah was a "bad guy", but he showed integrity. He obviously considered his word to be his bond, and wasn't about to throw it away disingenuously. Likewise, Moroni responded with similar integrity, giving his Lamanites back their weapons before resuming the conflict. He didn't have to do that. Finally, after Zerahemnah lost his scalp to a Nephite swordsman, he decided he was indeed licked, and made the required oath. And he apparently kept it; the Book of Mormon records nothing further of him.
This shows that while the Lamanites were indeed wicked, they sinned primarily in ignorance, driven by the traditions of their ancestors. In contrast, the Nephites, having received the fulness of the Gospel available at the time, sinned against the light when they fell into transgression. The final chapter of this distinction was played out at Cumorah in 384 A.D., when 230,000 Nephites lost their lives in a final battle against the Lamanites, resulting in the end of the organized Nephite nation. The Lord distinguishes between ignorance and malevolence.
The LDS Church has also produced a series of Book of Mormon stories in print and in audio which are geared more towards children. Nevertheless, anyone can benefit from them.