We have sailed out of Pier 27 twice and it has been fairly uneventful. Once you get past security you will have the priority boarding and will be directed like at other ports. As others have said the line to get into the building and through security can get long in the morning. We always arrive very early so we got through it quickly but then had to wait in the terminal until they started boarding. We were in a Mini Suite on Princess both times so were second as far as priority so we boarded just after the suite guests.