I rate this documentary at the level of a one hour TV piece. I found it useful to understand the French point of view on the Duke and King. That POV is somewhat at odds with the more familiar English version of the facts. By the facts, I mean the facts upon which William's claim to the English throne is based. There are historical and legal quibbles about who pledges what to whom and when but it hardly matters. William became King of England, a nice promotion for an ambitious French Duke of dubious heritage. Winning counts a lot more than lawyerly quill scratching.
I found the account of the Battle of Hastings to be fair and accurate, so far as I remember from my study of the events in English language writings. The costumes and weapons of the actors all seemed authentic. I like that as it gives the modern viewer some sense of what it looked like to live a thousand years ago. I especially liked the use of the Beaux Tapestry to explain how the invasion and battle evolved. The narrator took pains to explain that the Tapestry served as a propaganda effort for William and that we should be careful about giving it more credulity than it merits. I found that generous from the French perspective.
I did learn about some of the building projects of William in Normandy. The scale of castle building in England really staggers the imagination. The narrator claimed that the number of castles in England went from five in 1066 to five hundred just a few years later. I would have liked the film to mention the rather primitive earth and log castles, the motte and bailey style castles. The soldiers of William put them up quickly to nail down the countryside but the film let us think that the castles were all the stone fortifications of our imagination. I took off a star for that omission.
All in all, this is a useful introduction to the subject, emphasis on introduction.