Interview experience:
We had one of the first interviews of the day (7:30am), and were allowed to enter the building just before 7am. A few couples were summoned before us, and it seemed like the US citizen partners were being sent back to their seats. This was the same when we were called, my wife was sent back to the waiting room and the agent proceeded with just me. We had a little bit of small talk on the way to his office, mainly about the Super Bowl which had been the night before.
Once in the room, I took an oath to tell the truth, confirmed my name and address, and had my passport, green card and driving license reviewed. We then moved on to the Civics questions. He stopped after 6 questions since I had got them all right. I don't remember all the questions, but one of them was why the US had fought for independence from the British, which I reckon he asks all the British applicants! I then did the English test, and the agent remarked that he had suspected I would have no issue given I am a native English speaker.
Next, I was asked a handful of easy questions about my wife, job, and son - when we married, any previous marriages (no), any period of separation (no), what I did for work (there was a major news story in my professional field about a year ago, so we talked about that), when our son was born. I had an envelope of additional evidence with me, but ended up not needing it. I did show him a picture of my son, mainly because I love showing people pictures of him, rather than being asked. Then the usual questions about any past crimes (none) or immigration issues (none). We had a little bit of small talk in between questions while the computer system loaded. I generally kept the small talk fairly vague, I've read about not giving away extra details on the off chance they are used against you - not that I have anything that could be!
Once we had worked through a few more things (more verifying of details, going through the specifics of taking the oath), he let me know that he was going to approve me once the system had caught up. He was unable to give any specifics about when I might hear about the oat ceremony though. Overall, it was a really pleasant experience. The agent was friendly and informative, telling me the reason behind each step of the process, and he seemed genuinely pleased to be approving me. All my experiences with USCIS staff have been good, but this was by far the best.
He didn't say, but I hope I will be a citizen within 1-2 months.