My fiancee reports that the interview process was very smooth. Officers were nice and there were minimal questions. Her actual interview was around 5 minutes. Overall time in the embassy was around 40 minutes.
A few things to note:
Don't arrive too early. You will not be let inside more than 30 minutes before your appointment time and waiting outside is discouraged.
The interview experience definitely varies based on your specific case. I've known my fiancee for over 5 years and visited a lot during our LDR. Others that only knew their fiance for a year faced a lot more scrutiny.
Questions:
What does your fiance do for a living?
When was the last time you spoke?
When was his last visit?
Where does he live?
And that was it. Visa approved and should be ready in just over a week from the interview.