Read some of the reviews from the ship just to set proper expectations before you arrive. The ship is beautiful, the ports... well it's Hawaii, they're all great. The service and cleanliness will leave a bit of a bad taste in your mouth. Going in knowing what to expect is important with NCLA.
On the ground transportation issue, they offer transfers but I'd grab a cab. It's only 5 miles but will take you approx. 20 minutes, traffic is heavy most of the day.
Have a great vacation!