I brought over the equivalent of a few thousand USD (combination of traveler's checks that turned out to be somewhat of a hassle and cash) for a few weeks and was able to exchange it at the Bank of China pretty easily for 6.8. Now, note that they of course charged me a transaction fee of $15USD, so it worked out in the end to be more like a 6.77 rate, but certainly still better than that BoA posted rate.