As a Chinese, I'm disappointed that although the movie features prominent Chinese characters and dialogue, the actors who play them do not speak proper Mandarin, so most parts of their dialogue are not recognizable to a native Chinese speaker. This takes away heavily from the immersion.
The naval battle scenes are played out well, and the best part of the movie is the seemingly one shot take of ordinary soldiers from the three main factions fighting on the ship decks.
I will give this 3 stars, it would be 5 stars if they actually had proper Chinese speaking actors play the main Chinese characters.