For me, this is the perfect heroic fantasy. Anderson is a magnificent prosodist with a unique voice falling somewhere between Dunsanian beauty, Howardian savagery, and the fatalism of Greek tragedy.
The setting is a Northern Europe during Christianization, indigenous gods and fays coexisting in reality with the Triune God, the balance of power seemingly hinging on the strength of human belief. Fertile ground for great themes, and Anderson works it well.
The author is also a master of action. Truth be told, I often lose interest when reading battle scenes, but never once did I here because Anderson's words move with the rhythm and speed of combat. I'm reminded of the best translations of Homer. Really.
I have often thought of how fantasy literature might have developed were it not for the Brobdingnagian influence of Tolkien. As is often noted, The Broken Sword was first published in the same year as The Fellowship of the Ring. In a way, it represents a road not taken.
Essential reading for genre fans, and also recommended to anybody who just appreciates a good novel.