The interviewer was a nice young lady.She asked me to raise my right hand and swear to tell the truth, and then she asked 4 questions:
1) How did we meet?
2) What are my plans when I get to the US?
3) Who attended the engagement?
4) Tell me more about your engagement
It took about 15 minutes in total. However, I had to wait 5 hours in the waiting room until it was my turn, since they finish all the non-immigrant visas first.