Yes, everyone had to disembark and go through immigration this morning. You were not allowed back on the ship until everyone was off. We chose to walk down towards Chelsea Pier and away from the crowds. I now have a U.S. stamp in my U.S. passport.
We were told that we would be called by deck, starting with 8. Seven was called not long after 8, and then 6 within a reasonable timeframe. We were on deck 5, and we waited for a long time to be called. When we saw no one leaving the ship, we decided to just leave. Immigration had about 6 lines open with at least 1 dedicated to non-U.S. citizens.
Tomorrow, as a PP stated, we go through customs. Some passengers did decide to completely leave today. Since we paid for 11 nights, we were staying on the ship.