I applied for a multi-entry visa to China, got it on the first try.
I went in November 2012. I'm going again in June 2013. Maybe one more time before the year is up.
One possible pitfall to watch for is that if you are not staying at a hotel, you are supposed to register with local police when you get to your girlfriend's place. I tried to do this when I was there last week. My girlfriend said it is crazy, and that we should not bother. I insisted that I would like to try to follow the rules. So we went. But only a deputy was on duty, he said we had to come back another day when the boss was there. So we came back, talked to the boss. He said we need to have certain photos taken for their paperwork. At that point, we said "forget it."
I'm going in June, and will try again to do it properly. Bring the pix, so they are ready.
A guy from another forum warned me that if I don't get registered properly while I'm there, China will reject me next time I apply for a tourist visa.
So my advice is to have your girlfriend get the photo/information requirements from her local police to you before you go, so you can have the info ready when you arrive, instead of wasting your precious time when you are there trying to get it together.