I've only had a vague sense of what the Spanish incursion into the Americas was like, from school or whatever other sources I've happened upon. Something about them forcing Christianity and generally massacring the peaceful indigenous people with guns. I got a different sense of things reading Bernal Díaz' account. These are some of the things that stood out to me:

• Hernan Cortes' campaign was only undertaken with the thinnest of government authorization, with several parties actively trying to stop him -- not because they thought it was morally wrong but because they wanted the spoils for themselves.
• There were a lot of people in Central America, with a large civilization.
• Díaz and his fellow soldiers seemed fairly devout in their faith, often ascribing their survival in battles or other good fortunes to the grace of God.
• Despite that, they seemed pretty OK with accepting Aztec women as gifts of diplomacy or trophies of war. Was chastity not an important virtue?
• Although they taught Christianity, one of their primary goals was steer the Aztecs away from their religion based on human sacrifice and cannibalism.
• Cortes was deft at diplomacy, gaining allies among various groups of Aztecs and generally tried to avoid fighting (until he got himself in such a precarious situation that taking Montezuma hostage was maybe the only way of surviving).
• Yes, there were muskets, but crossbows were also heavily used in battle by the Spanish.

The story is well told, including a "darkest hour" in the siege against the lake city of Mexico, when the Spanish have lost a battle wherein Cortes was nearly killed, many Spaniards were captured and sacrificed to idols, and their native allies abandon them.