An entertaining mash up of Middle Earth and Narnia set against a culture drawn from Anglo-Saxon, Celtic, Norse and Christian elements with a dash of the Arthur tale. The very cultures which competed in Dark Ages Britain while the Arthurian legend birthed.
It works better than it sounds. Because the story focuses on the young protagonists, the reader is not burdened with more than hanging on for the ride. Briggs is neither a Tolkien nor a Lewis, but he tells a good story.
One of the better transitions from this world to that of fairy. Once there, of course, the boys just want to get home. Not so fast.
Extra credit for managing both a satisfying climax to this story and sufficient hooks to the rest of the saga. Many contemporary authors propel you toward book two (or twelve) without bothering to entertain you in book one. Briggs manages both.