It was easy, the immigration officer did question my citizenship which I find odd other than that confusion it was a smooth interview.
my wife was asked mostly about my family and how her family reacted when we told them about our engagement and then I was asked what are the names of my wife's parents. the interview took us roughly 20-25 mins. same as the waiting to be called in for interview.
Interview was 02/15/17 Status Changed to APPROVED 02/16/17!!