nothing. however, when there is deflation it usually comes with a slowing economy. just deflation alone would be great, but it doesn't just happen by itself.  as another anon said, it's also bad for china's exports if their currency strengthens. but they peg their currency to the dollar, so its sort of arbitrary and the us (their biggest customer) has never cared about the trade deficit. soni don't think it really means much.  the last big point is that china needs like 6% growth to keep everyone there busy. so even 1-2% growth for them is a disaster. at least smart economists says this, but we don't ever get a clear picture of their problems. the evergreen collapse was the last big thing to hit them and so far it appears they've absorbed that. but a fin crisis takes time to heat up. us sub-prime blew up in like '06 or '07, the economy didn't get smashed til '08 and '09.
United States