Just returned from a 7 day cruise to St. Martin, St. Thomas and Nassau. We were looking forward to experiencing the "super-sized" vessel. We've cruised once on Celebrity to Alaska and then been with NCL in Hawaii, Mexico and Western Europe.
Flew into Ft. Lauderdale/Hollywood, primarily because of Southwest. Arranged shuttle with SAS who provided superlative service to and from Miami cruise terminal. Embarkation was hassle-free. Based on the signs, it appeared you can enter the terminal as early as 10 (and I noticed people were already checking in at about that time yesterday as we were waiting for our ride back to the airport). We went directly on board on arrival a little after noon and went to Garden Buffet for lunch and to wait for rooms to open up - 14th deck was ready at 1:45.
Our 10 year old thoroughly enjoyed the children's program and was able to enjoy the freedom of checking in and out herself at this "tween" age. We all liked the waterslides and deck area - there seem to be enough chairs. The buffet was excellent and able to accommodate the crowds - didn't do any dinners there but expect it was the same.