I have not sailed on any of NCL's newer ships, but have sailed NCL in Hawaii. Not a perfect cruise, but none are. On the other hand, cruising on a garbage scow and eating McDonalds would be heaven. After all you are crusing in Hawaii.
If you have cruised before the freestyle may take a bit of getting used to and the novice may find "navigating" 10 or 12 food choices a bit daunting for the first day or two. Eventually I believe everyone will fall into a groove and enjoy it. Again , the destination is the thing on a Hawaiian cruise.
The various overnights give you the great ability to see more and do more.
On Maui we were able to check out the town of Lahaina, do a long (and great ) catamaran/snorkel tour to Lanai, experience the nightlife, take a multistop island tour and still get in some significant shopping time.
May I be so bold as to suggest some things for you folks to check out?
1) If you spend extra time in Oahu your "must dos" would include Pearl Harbor Memorial and the Polynesian Cultural Center.Huanama Bay for beach and snorkelling, North Shore surfing (just watching is a sport in itself).
2) On Maui. If you do a Luau, do Old Lahaina. It is by far the best on all the islands.
If you do not do a Luau, check out the very unusual show called Warren and Annabells in Lahaina. You will be thoroughly entertained. For touring , you will not have enough time to do the road to Hana. To do it and enjoy it completely you need 10 to 12 hours.
You may want to do sunrise at Hakeakala. Other things to see, Maui Plantation (take the tram tour) , Iao Valley(spectacular scenery), Maui Ocean Center (might be the best "seaquarium" anywhere. No whale or dolphin shows, a little more scientifically oriented). Snorkelling at Molokini (best trip is run by Four Winds II). Almost any boat trip on the channel between Maui and Lanai will become a whale watching experience in January.
3) Kuaii Try and take an all day comprehensive tour. Let someone else do the driving.
Waimea Canyon is a several hour ride and you will also want to see things like the spouting horn, Wailou Falls and Wailou River, Fern Grotto and more. Napali Coast by air or by sea.
4) Big Island- Volcanos , Orchid farms, Macademia nut plantation on the Hilo side.
Snorkelling on Kona or Hilo side ( prefer Nelsons point on Kona side) .
Any Island, Beaches are spectacular, try them out.
Enjoy your cruises.