During my recent travels in Thailand, The Green Hornet was released in Asia...so, of course, I went to see it the very first day that it came out (as a dedicated Jay Chou fan).
Let me just say, seeing a movie in Thailand is interesting anyway...you stand for five minutes at the beginning of the movie in honor of the king while they play the anthem and show video footage of him. But anyways....we really liked the movie (and in fact went to see it again the next evening and later bought a bootleg DVD of it...hey, I did my part in supporting it in the theatre).
So, my review is as follows:
While I am a big fan of Jay Chou, I honestly didn't know what to expect...I knew I would think his English was cute, but honestly didn't expect for it to be great, and didn't know if he would really be able to pull off the subtle humor that the dialogue required....but he definitely did.
I am also not a big Seth Rogen fan, but I found him pretty funny in this movie. The movie itself is an anomaly, and I think a very good one, in that its treatment of Kato as a character is really positive for Asians....without turning him into a flawless martial arts god, they made Kato the "cool guy" and true hero of the film, while still allowing him character flaws (though admittedly not to the extent that Seth Rogen's Britt Reid displays as he deals with some major insecurities of playing second fiddle to the "sidekick".
The dialogue and fight scenes were entertaining and actually really funny, and the chemistry between Jay Chou and Seth Rogen is great. Cameron Diaz also is limited in screentime, which is probably good as she wasn't exactly super-convincing as the brainy Lenore Case.

Britt: "Sit with me Kato. Tell me your tale."
Kato: "I was born in Shanghai. You know?"
Britt: "Yes, I love Japan!"
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Apparently there are already talks of a sequel...which I fully support. It's about time Hollywood featured a cool Asian...not the stereotypical "funny guy with accent".
One of the most enjoyable aspects of the film for me (aside from the typical education that comes from highlighting cultural differences and someone's assimilation to a new culture) was the portion of the story that showed him growing up during the Cultural Revolution in China, and the affect that this had on dance as an art form in China. Particularly touching is the depiction of Li's dance school headmaster and his subtle rebellion against the communist regime, and the way in which events play out.