ONLY THE THRID PARAGRAPH CONTAINS SPOILERS!!!!!
Let me start off with the things that might affect your decision. The fighting is not realistic and there are creatures not known to man. The actions in the movie contains live action. It mimics animes. The acting was very good though. The live action should not render you from watching. Even though this film does include history, it's very fictional. Some characters or groups of people do not exist. If you look above (if it hasn't been changed yet) this film is rated G. It shouldn't be, there is cursing, bloodshed, and graphic violence.
Now the good parts. The acting is very good. The story and plot make since, so there shouldn't be confusion. This movie contains humorous moments the break the serious ice. The fighting scenes keep you intact. The quiet moments are not quiet, watching most movies, we hate the quiet moments,but in this movie they don't last long. The visuals of the scenes are amazing and cool.

SPOILERS!!!!!
The first 5mins was a childhood story then it transitions to a teen life. Shin and hyou are "brothers" for life. Hyou is scouted to serve the king, while shin is left behind. Shin gets stronger to, one day, meet hyou again to become "Great generals under the heavens". Hyou comes back to there plantation bleeding and half alive, he sends shin on a quest to find the king. The king is hyou's look alike. The truth was revealed, hyou was scotted to be a decoy if anything ever went wrong. Hyou was killed by the enemy, thinking he was the king. The king, Sei, after clearing up the confusion, then gathers his soldiers, shin and ten (a girl mountain person) and try to revive the alliance between the mountain people and his people. The mountain king, turns out to be a woman and agrees to helping Sei, the king, to reclaiming his throne. Sei reclaims the throne and reveals his true reasons for wanting to be king, to rule over all of China in harmony and alliance. With shin by his side, and the life of thousand if not millions, he can accomplish this dream, just like shin can become "Great general under the heavens" and make his "brother" proud.

Please do keep in mind I'm not good at this but I think, this review should help you make your decision. Please watch this, it doesn't disappoint.