Just had interview last week. Make sure to bring the passport, green card, driving license, SSN card, the interview letter, and any documents required in the letter. I forgot bringing my SSN card, but seems it is not too big a deal.
After asking me swear,
First, the interviewer followed every questions on the N-400 form I filed and recoonfirmed every answer, such as what is your current address, which company I am working for, what I am doing, am I associated with communist party, are my parents associated with communist party, etc.
Second, he looked at my passport and found the latest stamp and asked me how long I stayed outside of US. I think that he tried to fill the time gap between the form being filed and the interview date.
Third, let me choose to take new test or old test. Then, followed by reading 3 sentences and writing 3 sentences. Very easy.
Good luck.