Pat Morita's performance is certainly one of the most remembered parts of this film. He seem to portray Mr. Miyagi just as he should be portrayed. He is a nice mostly stoic Asian man who helps obnoxious Danielson (Ralph Macchio) learn how to fight against the evil Cobra Kai bullies he must face. Morita has the stoic, slightly humorous manner of Miyagi down well in the film. Is this amazing acting, no, but it does technically work well for the part.
I will admit it I do sort of like his performance, everything he does simply does technically work for the character of Miyagi even if it is not amazing. One thing many might not remember though is MIyagi is not quiet overly easy on Danielson as in the sequels. Morita technically is fine in the teaching scenes doing his best to sell the odd methods of Miyagi's training. He adds humor well enough when he can and his chemistry with Macchio actually does work well with what the film is going for.
One other part of Karate Kid that might not also be remembered is Morita does have an Oscar scene. The scene consists of him being drunk and "celebrating" his anniversary with his deceased wife. I thought Morita was fine in this scene, and in fact slightly effective in his very fast breakdown scene. This is not great scene, and actually does not entirely fit the rest of the character, but Morita is fine in it. Besides this scene though he keeps his character stoic and semi humorous, and is fine my opinion. His performance is nothing special but what he does fits his character.
