I have watched The 13th Warrior over 20 times.

Rating: 10/10 (27 November 2016)

This is one of the best "medieval" movies I have ever seen, and I've seen a lot of them: El Cid, Braveheart, Excalibur, The Hobbit and The Fellowship of the Ring series, Ivanhoe, Adventure of Robin Hood, and the unlisted Prince Valiant. I have watched The 13th Warrior over 20 times.
The music is very good, the story is believable: hominid anthropology overlap credible, holds together well, and I have always thought the film's portrayal of Ibn Fahdlan's learning transition, learning Old Norse by listening quietly to the other characters, makes his (our) transition to understanding all of the characters speech quite believable. Good job, there.
The battle scenes are great, well constructed, lots of long-shot perspective, avoids cheap close-ups, the cannibalistic bear warriors fierce, the horse riding first rate, and the cave fight scary. As I do not like enclosed spaces, this portion is very believable.
While the only notable actor, besides a short cameo by Omar Sharif (Melchisidek), is Antonio Banderas (Ahmed Ibn Fahdlan); I thought the ensemble acting of the others including Dennis Storhøi (Herger) Vladimir Kulich (Buliwyf) were very good. I have yet to see these actors, except Tony Curran, anywhere else.
The only complaint I have is the geography. As a geographer, I know full well that Scandinavia can be, for the most part, short on coniferous forests. I deduced that the filming was done, not on location, but in Canada, which I found later to be true. Admittedly, it was probably cheaper to shoot in Canada, and made the story more enjoyable with a few more trees.
I am amazed that there are those who've submitted reviews on this site, who rated the abysmal Conan The Barbarian higher the the The 13th Warrior! Honestly, after reviewing the movies on the Best Medieval Movies Of All Time, I cannot think of a better movie than The 13th Warrior.