I hear lots of stories about how crap they are, but the two owners of chinese bikes I know seem to have had little trouble.
A guy told me the other day he bought a Chinese carb for his Honda CG. It cost £25 and went straight on with no fuss. The bike ran better with that carb than it ever had with the Honda item.
All they have to do os nail the quality issue and they will take over the (biking) world.
GC