Inverview experience: Interesting to see all these "nice officer", "good officer", "courteous officer" blah di blah di blah messages. My experience was completely the opposite. Right from the get go it was clear that the officer was not going to approve me. Very terse tone, almost like an interrogation, and the interview took over an hour (!). I was questioned on every line, with the officer making extensive notes (all in uppercase), with quite a few details that appeared irrelevant to me put in big uppercase on my N-400 (such as that I was renting, and had not yet brought a house, that I travelled 4 times to India, that I was a contractor at Big Evil Bank, that I claim that I have no children other than those listed on the application, that I claim I have been married only once etc) (officer actually wrote this stuff in big uppercase: 'applicant claims that he has only been married once', 'applicant claims he has never been arrested abroad'). In the end, my case was not approved.
It seemed to me that the officer was just looking for something to deny me on, and because there was not much else, they came up with an nice original one: the fact that I had other US visas on my passport (B1/B2s obtained prior to coming into the US for employment) that did not have 'cancelled' stamped across their face. The great idea was that I might be lying and might have travelled on a B1/B2 after receiving my green card! Well. What can I say. I might just have been told that I do not qualify because I don't have purple hair. I said that is not something I control, I don't issue visas, and I don't cancel them. The same passport had been provided for the employment visa to begin with, and thereafter for the green card, and the US visa authorities had ample opportunity to cancel anything they wanted to.
Finally I was handed a sheet that neither approved nor denied my application, and the officer said I will receive an N-14 in the mail after my application has been reviewed thoroughly. So I am waiting for them to invent something weird.
I went in thinking there was really not much to my case - straightforward, and clean as a whistle. I have an employment based green card, just the one same wife from many years before I even thought of coming to the US, no arrests, no DUI, not even a single traffic ticket in the last 8 years here. All taxes filed timely, paid, but aaha - that B1/B2 visa... Gotcha!