The film is a loose retelling of the legend of Siegfried and Brunhild as swords-and-sorcery viewed through a soap lens.
Weaving a complicated plot, with inevitable unhappy ending, it's easy to see why Wagner would want to adapt this story.
The acting is fine for what it is and you can't help but be distracted by the gorgeous Kristanna Loken (T-X from Terminator 3: Rise of The Machines), perfectly cast as Icelandic warrior-queen Brunhild and the lovely Alica Witt as naïve Kriemhild.
Great scenery, slow-motion bundles (it's a bit of an exaggeration to call most of them 'fights'), arch acting and above-average CGI make for a great little pot boiler.
It's quite long (around three hours) but The Sword of Xanten (aka Ring of the Nibelungs) is non-stop fun and frolics all the way - with a bit of sauciness and a bit of blood - that can hold the attention of a willing viewer.