The figure Mulan is based on a traditional Chinese ballad about a young woman who became a warrior. There are lots of adaptions so why should you watch this particular one?
I recommend to watch this version because it's simply the most accurate adaption that I've seen yet.
I have watched and loved the animated Disney version of Mulan as a child and it still has a place in my heart, but for the mature audience this one is probably the best version.
The movie tells a realistic story with depth and an outstanding cast. It does not make it look like Mulan won the war within a couple days but actually refers to 12 years of war, which makes the audience understand why her character seems hopeless at some point.
The Disney remake was too 'fantastic' in my opinion with witch and magic. Mulan - Rise of a warrior proves that you don't need fancy costumes or CGI effects to tell a captivating story.