My VI was on today, 5th of Jul 2013. 7:45 AM slot.
The rejection rate on that day could be around 70% to 75% but most of the rejections were very obvious. I could see that most of the people with good confidence and clear intentions (as I heard in their answers) were getting visa approved.

Me : Good Morning !!
VO : Good Morning, How u doing?

Me : M doing great, Wishing u belated Happy Independence Day
VO : A witty smile(as if he knew, i was buttering him)

VO : Which colleges did you apply to?
Me : N.E, U.H, MTU, UTA and IIT,chicago

VO : Why UH over other college?
Me : told

VO : Who are all your sponsors?
Me : told

VO : What do they do?
Me : told

VO : Assests?
Me : told

VO : tell me about bachelors?
Me : told

VO : What about current job?
Me : told

VO : do u know n e 1 in US?
Me : told

VO : What about ur siblings?
Me : told

VO : Why is your elder brother not sponsoring you, instead of ur brother in law?
Me : told

VO : what after MS?
Me : told

VO : Ok, I am approving your Visa, It will be delivered to you in 2-3 days.
Me : Thank you sir !!

Yes... with these questions asked and no document checked, my visa was approved. Perhaps luckiest day in my life.

- Keep answers "short and sweet"
- Try to be confident and speak with clear pronunciations. do not ask to repeat questions often, they get irritated easily
- Smile adds some charm and makes conversation pleasant.
- Y this college over other,this question was asked to everyone, prepare it thoroughly

All the best for your VI !!