We returned yesterday from a wonderful NCL Dawn cruise to Florida and the Bahamas. After reading some negative comments on these boards, i was a bit concerned prior to sailing, but had and absolutely wonderful cruise vacation, and would recommend this ship to anyone!
bus service: prompt and efficient. (note that you will arrive later at the pier when taking the bus service -- approximately 1:30 pm) and also you cannot use express debarkation, but this was not a problem and the bus made the trip to new york stress free.
embarkation: relatively smooth, although arriving in the afternoon makes the lines longer. go early (11:30 am) if you can.