Concur with both points above....
Photon works great on China Unicom or China Mobile (I think Unicom has the faster data speeds).
OR if you are going to be traveling alot within China or Hong Kong; and money is not a huge concern (ie work paying the bill) just get a roaming card from Three in Hong Kong. Fantastic service, and easier roaming. (with China Unicom or china Mobile, you have to have a different SIM in each locality (ie Shanghai is different SIM card than Beijing etc etc.) The 'Three' card works in all of China as well as Hong Kong. 98hk(like 12 USD) per day when roaming, 28(3.5 USD)when in Hong Kong.
If you have to go with one of the China providers, get a dual sim phone if you plan to travel between two different areas much. Saves at least SOME hassle, and I think there are even phones with THREE sim slots as well.
Also, if you are going to have permanent residence, you can get post paid service which is easier because you dont have to worry about refilling your balance....
"Adults are just obsolete children and the hell with them."
— Dr. Seuss