Why is? Without giving too much ...:
Ancient demons terrorizing the old Korea. Battle-Mage face them in opposition to the main characters is a particularly powerful as narcissistic representative of this guild. As magicians like demons are virtually immortal, it is no surprise that they also deliver this fight at the present time. Thus, the film spans over several centuries.
Of course, a little love story and private rivalries there also.
Good:
+ Charming costumes and landscapes
+ Plenty of wit
+ Imaginative characters
+ Beautifully staged fights and magic
+ Unconsumed history with many small surprises
Poorly
- Acting possibly something very young hero
- Partially something overexcited (Asian Humor halt ..)
- Computer-animated demons move .. quite stiff
Conclusion:
For fans of Asian ghost and demons films a MUST! No "Crouching Tiger, Hidden Dragon", but certainly with its own unique charm!