This is one of those films where an attempt to describe the plot is largely doomed to failure. Still, here goes... Two snake demons, Susu (Huang) and Qingqing (Choi), see herbalist Xu Xian (Lam) gathering materials; Susu falls for him, adopts human form, and the two fall in love. Qinqqing, meanwhile also falls for a human, the apprentice to demon hunter Abbot Fahai (Li), who is bitten by one of the creatures the pair are hunting, and starts to turn into a demon himself. The Abbot tracks down Susu and Xian, knowing that only trouble can come from such a relationship, tells Susu to leave her now-husband, or face the consequence. She doesn't, and the consequences involve her being stabbed with a spirit blade by her husband. The only cure is a special herb, kept in a mystical pagoda: Xian retrieves it, not knowing that by so doing, he has freed all the spirits which the Abbot had trapped in the pagoda.
But, wait! There's more! However, let's just leave it at that, as it's enough to give you a general idea. To be honest, the story isn't all that great, with way too many unanswered questions, such as the Abbot's acolyte, who vanishes randomly about half-way through. And I have to wonder, why is it that literally every woman in this is a demon? Best not worry, and concentrate instead on the good stuff, which is some impressively imaginative visuals, and decent battles - though it seems that so much of this is CGI and wirework, there was hardly any point in having Jet Li in there. Does take some time to get there, with the first half being more interested in mushy romance and comedic moments that hardly raise more than a smile, though I did like the idea of the Snakes having a family of other animal spirits [the mouse is cool]. The finale, however, largely makes up for that, in terms of mad spectacle, even if it looks more like a particularly lurid video-game. Definitely works better as eye-candy than a coherent movie.