An...interesting...movie experience
This movie was great fun to watch...possibly because I was laughing incredulously and making sarcastic comments the whole time.
The movie seems to be composed largely of a series of completely random coincidences. The ship's raggedy captain suddenly reveals himself to be the Spanish court lady's father. The samurai escapes from prison JUST IN TIME to save his "young lord", who has coincidentally escaped at exactly the same time.
There are also some things that are SO FAKE it's unbelievable. For one thing, I'm no sailor, but I doubt that you're supposed to leave all the ship's sails up in a wild storm. And that completely impossible and really fake-looking backward somersault in one fight scene was BAD.
That being said, I must admit that the movie wasn't ALL bad. It had interesting bits of East/West contrast, such as a great contrast shot of the Japanese and Europeans praying, Ye Olde Katana-versus-Toledo-Steel debate, and the crowning scene of a JOUSTING MATCH between an armored knight and a samurai with a spear.
The ending was wonderful, actually. The Moroccan sultan's last line ("...infidel, you teach me the meaning of honor") was memorable and quite uplifting. The skinny red-haired boy's promotion to captain was funny. The samurai's expression when the lady kissed his "young lord" was PRICELESS. And the very last line..."under perfect conditions, forever"...aah! So cute and sweet!
So basically, I spent most of the movie laughing and being loudly sarcastic, and the last five minutes loving it. If that's the experience you want to have, you're welcome to watch it.

Without question, the worst movie I've ever seen!
I can't believe anyone would make a movie like this! This flick is a classic example of ignorant people assuming that Asian Martial Arts are the best in the world. The moronic stunts that guy pulled with that katana are impossible! No sword, least of all a katana, can slice through good European plate armour like that! I refer the reader to the recent record-setting "kabutowari" achieved by Toshishiro Obata. This cut holds the world record, and measures a mere handful of centimeters. None of that "slicing helmets in half" crap in the real world. People wore armour because it worked, folks. And there are people who've seen this movie who totally believe this fiction.

History lesson: European steel and metallurgy was vastly superior to contemporary Japanese sciences. Native Japanese steel occurs only in extremely small deposits of black iron-bearing sand, called tamahagane. The excessively complicated process the Japanese smiths developed for forging a sword was necessary due the the incredibly poor quality of their ore. Moreover, the technique of combining hard, high-carbon steel with softer, more resilient iron was well-known in Europe during the Dark Ages. It was employed by the Norse centuries before their ever was such a thing as a katana. Europe's technology had advanced sufficiently by the time the Japanese got around to it, and it was all but obsolete in the West. In fact, when the Europeans first showed up in Japan, the Japanese almost immediately begin European metal. Finally, many, many samurai wisely imported European armour, recognizing that it was far more protective than their own.

For further reading, I recommend: Arms and Armour of the Samurai by Ian Bottomley, any of the Osprey books by Anthony Bryant, and anything by John Clements for comparison of Western and Asian martial technique.

Great Movie
Excellent movie... But Sho Kosugi plays Mayeda not Toshiro Mifune.

Swashbuckling tale of shogun warriors
This video was originally released in the UK as "Shogun Warrior" and stars David Essex as an evil Spanish nobleman who is determined to win the day at all costs. Nothing stands in his way, except a heroic shogun warrior called Mayeda, played by Toshiro Mifune. Great combat scenes and a particular nasty ending for the evil Don Pedro. Has a love interest too as the shogun battles to save a ladies honor from the clutches of Don Pedro. Also stars John Rhys Davies (famous as Indys arab sidekick in the Indiana Jones Movies). Altogether a very enjoyable tale of tragedy, love and adventure.David Essex fans will not be disappointed.