"The White Haired Witch of Lunar Kingdom" is based on "Baifa Monü Zhuan", a novel by Liang Yusheng. The story resulted in several previous films, but I have not seen any of them, so I cannot compare this new version with the old. However, I assume that these earlier films are more watchable, as they wouldn't have relied so heavily on CGI and wire stunt work--something which actually seemed to detract from my enjoying the movie. In other words, there were so many crazy stunts and magical happenings that the story itself seemed secondary--especially the crucial romance between the two main characters.
The story begins in the late Ming Dynasty in China. The country is beset by foreign invaders as well as disloyal schemers within the government. However, to hide their scheming, the plotters have implicated Jade in the assassination of a governor. This is complicated because the witch, Jade, has fallen in love with Zhuo Yihang--the man who is the governor's grandson! So, Zhuo is torn between his love for her and his loyalty to the emperor-- and, for a while, he pretends to believe that Jade is responsible for the killing and no longer loves her. What is to become of the pair? See the film...though I wouldn't rush to do so.
There's MUCH more to the story than this...but frankly I had a hard time following the film. Much of this is because I found my attention span drifting often through the course of the movie. Why did I find myself so uninvolved with the film? Well, it all goes back to the CGI. Too often, the director focused on stunts instead of the story. The important romance seemed to take a back seat to cool slow-motion arrows, 'wire fu' stunts (where the various characters fly about as if by magic--much like you saw in Crouching Tiger Hidden Dragon) and an overly complicated story. The bottom line is that I have seen many Chinese epics that were satisfying and enjoyable from start to finish. This one, in contrast, left me feeling a bit disappointed and confused.