A big change happened around May 2005 (For Visitors)
According to my experience, a big change happened around May 2005.
It's very difficult and I don't think the situation changes. Only one good case the I know: My friend's parents got VISA because their daughter is in USA and the parents had been in there before.
I had a bad experience in August 2005. My parents and I went to the interview for their Visas to US and they got the rejection letter.
I hope this message will save your time and money (100 US$/person).
my experience was negative also. They told me if my mom had visa to US before, they can do it again here. But if she never get US visa from China before, she has to apply the first time in China. That's how I got rejected.