This movie was a lot of fun, it was like a mix of an Indiana Jones movie and a mystery film with a bit of film noir (It's never clear which characters can be trusted.)
The main characters are reasonably well developed and you won't be bored. The problem, and the reason I can't give it above a seven star rating, is that the plot is very convoluted. It seems that in almost every scene a new character is introduced, or multiple characters, making it very hard at times to figure out what is going on and who is talking about whom. Many characters are introduced, given names, and seem to be set to play a large role in the rest of the film, and then promptly disappear in one or two scenes. The other issue is that, while for movies like this, one expects to suspend their disbelief and enjoy things, at times the director expects you to believe some utterly unbelievable coincidences and plot twists.
All this being said, I still enjoyed the film and found it to be a fun way to while away a few hours in an afternoon. The interspersing of Chinese history made it enjoyable and it made me want to read more about the Tanq and Qing dynasties. The characters who do stick around for the whole film are interesting and relatable in their human flaws (greed, sloth, capriciousness, etc.) but, in some cases, their ultimately good heart.
Overall, I'd say if you're not feeling picky and are looking for a fun film that has a good pace, this is well worth a Sunday afternoon viewing. Don't expect to be blown away, but you won't feel like you wasted your time either.