There are many banks with many ATMs. Unfortunately only about 50% of these accept foreign cards. Still, this is still far better than supposedly modern cities like Tokyo, Japan.
The main foreign friendly ATMs are controlled by the Bank of China. Bank of China ATMs work in both Chinese and English (depending on your card), use the latest equipment, and are pretty easy to find. They do have a habit of being over-used though, so sometimes they are out of cash, receipts or whatever. Also, the connection to the overseas banking network tends to have a high down time.
If you are told by a Bank of China machine that your transaction has been declined and to contact your bank, do not panic. This often just means that the International network is unavailable. You should try the other two banks mentioned or return the next day.
If the Bank of China ATMs are not working for you, the next best bet is a Merchants Bank outlet (pictured above). Their network seems to be a bit more stable, and seem to run out of cash less. The problem is that Merchants Bank branches are few and far between. Finding one is often difficult.
Just recently another bank, the Industrial and Commercial Bank of China, has opened up most of its ATMs to the international network, allowing VISA transactions.