I would still hesitate to put my BTC in this exchange to trade with. I understand that there is now some level of evidence that they have sufficient reserves to pay all their BTC deposit holders (I didn't see anything about fiat based reserves), however it still does not explain how they are able to charge 0 fees but still remain in business.
I'm fairly certain they
do charge fees - just not for trades (or deposits). My Chinese is non-existent, but running Google Translate on OKCoin's
China homepage you can see they mention trades and deposits (no fee), but not withdrawals.
This site says (withdrawal) fees start at 0.1%.