At the time of the Korean war, China was still in the Mao period. From any sane point of view at that time, communism was horrible for China.

Post-Mao, well... Hua was a disaster and Deng was never a good communist. Mao himself accused Deng of being a capitalist and banished him to the countryside in the 60s. Once he finally gained power and brought back mild capitalism (really, market socialism), it still took 20 years for China to really get going.

If you define "the communists" as "the Chinese communist party", then judging from China's development they've done a fine job. This was not quite true during the 1950's, when the head of the communists was Mao.

It's also questionable to define the economic system of Deng's China as "communist" in the same way as Soviet Russia and, say, Cuba.