We went on the Norwegian breakaway in February. NYC to several stops (Florida, Bahamas another stop I can't remember!).
It was brilliant. We did the all inclusive option which was fantastic (and well worth the money) everything (apart from the usual al'aCarte restaurants) was included. Cocktails as well which are very nice! All branded drinks. The food was brilliant, the buffet restaurant was huge. Even at busy times you could always find a clean quiet table. So much choice, each night had a theme (DH loved Bbq night, steak, ribs, pulled pork, brisket... I think he'd go again just for the food). But each night there were also regular dishes as well, so salads, chips, hot dogs, burgers, fried chicken, pasta dishes, a live cooking station.
Dd was only 1 when we went but the kids club itinerary a looked amazing. They are open till something silly like 1am. Activities going on every day for them. We took dd to sensory and messy play while we were on ship and they had a small play room for under 2's.
We'd definitely go again, for kids I think it's fab. Plenty of activities, the pools were smaller than I imagined but were never busy. I was worried about it being busy but it was strangely quiet even on the days at sea there were always plenty of quiet areas to sit and read or watch the world go by.
The staff on Norwegian were also brilliant. We went to Canada before we got to NYC so we had quite a lot of clothes that needed to be washed because we'd tried not to pack loads. I went and spoke to the housekeeping person on customer services (because the sheet in the room for laundry didn't have an option for baby clothes) to see how much it would cost. She told me to just fill the bag and she'd do it for $25! Filled the bag with a mixture of ours and dd's laundry, it was back within 2 hours and she never charged us for it! I checked with her and she just said it was fine 
I sound like I work for them but I honestly couldn't have wanted more. We booked through Iglu cruises and they 'customised' (sounds posh) our trip to include another place before we went to NY, they sorted transfers, car seats etc. I'd recommend going through them.