Yes, the I-751 is still pending. We had received an 18-month extension, then later a 24-month extension. I think they are leaving the processing of all I-751 to do together with the N-400.
Yesterday my wife and daughter came to the building with me. The security guard let them in, but asked them to stay in the waiting room on the first floor. We had to go through a metal detector just like you would see in an airport. Put your shoes, watches, and belts in the box for scanning. My wife stayed on the first floor waiting room, while I went to the second floor to wait for my interview. We arrived a half-hour early, and I was called for my interview 20 min after my appointment.
The officer gave me the reading/writing test on a screen, then the civics test. After answering 6 correctly, he didn't ask me any more. Then he went through personal questions, regarding dates, addresses, birthdays, dates of traveling abroad, etc... I got the general impression he was checking if I would answer the same details as I submitted on the application. At the start he said he might ask to interview my wife for the I-751, and I told him she was downstairs, but he didn't require that in the end.
He didn't ask me for any supporting documents.
Finally, he told me that everything looked good, and that once he was finished processing the I-751 paperwork he would give me an approval. He said to expect a date for the oath ceremony sometime next month.
My wife's experience downstairs:
There is a large open waiting room, where people are waiting for their oath ceremony. There were about 15 rows of seating. There are bathrooms past the elevators. There was a sign saying no food or drink, but my wife gave something to my daughter to eat, and nobody said anything to her about it. The majority of applicants were there together with their families, and dressed up fancy, with dresses and suit and tie, or in their cultural traditional dress, because after the oath ceremony there will be a photo opportunity.
Applicants were asked to fill out a form, my wife said it looked (from far) just like one of the receipt letters we get in the mail from USCIS.
When the time came for the ceremony, a lady asked the applicants sitting in the front three rows to go first, while their families stayed seated. It only took about 15 minutes before the second three rows were called. At that point I came down, so we left before seeing how the photographs works. My guess would be that this will happen at the end, after everyone has taken their oaths.
