My experience at US embassy was very interesting. the interview was in two episodes.
on Oct 10, i just delivered the Documents, finger prints and pay the fees and i was told to come back next day to do the interview. (first day in details : http://www.visajourney.com/forums/topic/612772-k1-interviews-algeria-round1/
The second day on Oct 11, the CO was mean and tough. basically did not ask me anything just studied my file before and select some weak points and questioned me about it and what ever i answer he say " I'm not convinced" i heard this the whole interview. the points he insisted on are :
So the whole interview was like he ask about these stuff i answer and he reply " I'm not convinced". at the end he gave me back all the evidence i provided yesterday (pics, chats,...) my passport and a 221g form for missing medical that was not ready yet and said "we can not issue the visa now". I left the embassy with Zero hope. it was like 10 to 15 min but it seemed 2 hours. then after thinking about his last words and getting some advises from friends "specially Adam" I knew we were approved and nothing to worry.
The Whole interview was just bluffing and testing and that what the interview is about.
on Oct 17, I delivered the medical and passport and the status changed to ISSUED on Oct 19th. and Passport with the VISA in Hand Oct 23.