It's really good. The story and everything is okay, but the film is all about the action, it's got amazing fights, especially becasue of the lead Tony Jaa, he's an amazing;y agile martial artist and does some pretty amazing stunts.
Jaa's follow up film Tom Yum Goong is even better. You will definitely be impressed becasue his fighting style is unique and his athetiscm is amazing. Jaa makes Jackie Chan (in his prime) look about as mobile as Free Willy.