My opinion is the same, China Unicom is the way to go. I have had no problems at all except for occasionally traveling to remote areas and loosing the connection or having a slow connection. In the big cities it works flawlessly and excellently.
I guess the only other note is that I am not sure if the plan I described is the most economical. One other poster referred to buying a prepaid sim at the Bai Nao Hui (Buy now computer market). It sounded like his plan was a little less and perhaps easier to buy than the one I purchased unless you are fluent in Mandarin in order to shop at the China Unicom centre. The guys at the computer market are so keen to sell to you, you do not need to be able to speak Mandarin (although it will help).
I was just happy to get mine working at any cost so I was less concerned about the cost.