DigitalRev compared the Chinese Yongnuo clone to the original Canon EF 50mm f/1.8 II lens. While both lenses are made in China, the Canon model uses higher quality material and has superior design and quality control. There is more hilarity than surprise in this video clip but what's not mentioned frequently enough is, even if the clones work and may appear to be a 'good' value in the short run, they will turn out to be a bad choice in the long run, since their lack of reliability will inevitably come through with a little bit of time, perhaps right when you need the equipment to work properly.
I came back from a photo shoot in India earlier this month and my Indian friend commented to me some of the Canon models sold there are made in China and he was surprised to find the difference in the quality compared to the ones made in Japan. Moral of the story is, buy quality equipment, take care of them and they will do yoeman's work for you and retain its value when the time comes to sell them.