Outsourcing factory jobs to China is good in the short-term and significantly improves multinational companies bottom lines and profit margins. But in the long-term the loss of factory jobs results in higher unemployment in developed countries, local factories close down and consumers in developed countries may stop spending. Outsourcing lots of jobs ends up hurting a lot of people.
Cheap factories results in lower quality goods. The Chinese factory workers are exploited and paid extremely low wages around $2 a day. China also has a high rate of child labourers.