In our case was very easy and faster:
Rase your right hand, do you swear to say the truth... yes I do. (Both of us at the same time).
Then she asked me my name, birthday, city of birth, adress, work, country, my parents first names, if they are living in Mexico and all the questions that the answer is no in the forms, like be acused, etc...
After that she asked my husband the same about himself and how did we meet.
She asked us documents that proof our relationship (joint accounts, etc.) and that was it.
She approved and we are waiting for the letter of approval in the mail and of course for my green card.