How bad was communism for China?

This bad. Forty-three million dead from starvation and executions over a three-year period.

And China had its own Walter Duranty in the form of Edgar Snow:

Back in China twenty-four years later, Snow was pestered by news agencies enquiring about mass starvation. The Snow of the 1930s had gone into the field to see for himself a prolonged drought in the north-west, where people were rumoured to be selling their children. But this time he relied on his access to top officials such as Premier Zhou Enlai, and foreigners who flacked for China such as the New Zealander Rewi Alley. In the book he wrote about that trip, The Other Side of the River, Snow stated, 'I saw no starving people in China ... Considerable malnutrition undoubtedly existed. Mass starvation? No.' And most positively: 'Whatever he was eating, the average Chinese maintained himself in good health, as far as anyone could see.'

In brutal fact, between 1959 and 1962, at least forty-three million Chinese died during the famine Snow didn't bother to see. Most died of hunger, over two million were executed or were beaten or tortured to death, the birth rate halved in some places, parents sold their children, and people dug up the dead and ate them.

Another useful lesson in the destructive power of totalitarianism.