Good fight scenes. You could really feel the "Americanization" factor - the, "we have to include THIS/THAT for western audiences," and, "we have to include this/that or the KIDS just won't get it," and that really just pushes it towards dull and uninteresting. IGNORING the formula is just as appealing as BEING formulaic. People will indeed go to a certain movie because they can rely on getting just what they expect, but that doesn't mean that they ONLY want what is predictable and formulaic.
While the "American formula" elements were adequately enjoyable for what they were - grudging submission to formula - they were clearly OUT OF PLACE. It rankles through the entire movie and actually diminished my own enjoyment of it. If they really had wanted to take it in those kind of directions they'd have done VASTLY better by using a teen character from modern Hong Kong rather than New York/Chicago/wherever. Simply using English dialogue rather than subtitles would have been all the nod to American audiences they needed to make. While Chan and Li are not the superstars here that they might be overseas they have better drawing power than they seem to give themselves credit for.
If Chan and Li enjoyed this at all, and if it is at all successful, they owe it to themselves to make a movie that THEY want to make, in America, with a Hollywood budget, in English, but otherwise with open disregard for, "Oh, we have to do this and that to make it appeal to American audiences." It is their acting, stunts, skills, inventiveness that is appealing, not any given plot convention, featured character, or story element.
With all that said it's a great movie, though I otherwise did expect a little more teh funny.