In the extremely successful 2008 film 'Kung-Fu Panda', Jack Black finally got a chance to play himself, because, however funny he was in 'School of Rock' and 'Envy', he is just an overweight comic actor that wants to be a heavy metal star, just like Po is an overweight panda that wants to be a Dragon Warrior!
That film was quite funny, but this just drags all the gags along the Wall of China too far, and they eventually fall asleep.

Pity, 'cause after the awful 'Gulliver's Travels', Black needed to get back on track.
This is not that film