We have had some very good cruises with RC and Princess. This is our first cruise with HAL so our opinion is in comparison with RC and Princess.
Lets start with the positives. I found the quality of the food and entertainment to be good, and in many instances, excellent. I had a Barramundi one night that ranked up there with my all time best meals. Most meals in the formal dinning rooms were well prepared albeit sometimes overcooked (the seared tuna was cooked throughout, MR steak was closer to medium) but I attribute this to my 3rd complaint - older folks like there food overcooked. The cafeteria served some of the same dishes as the dinning rooms but generally at a lower quality which we was typical with other cruises also.
Some of the entertainment was lame but so was some on RC and Princess. W and I both enjoyed at least 5 of the 7 main stage shows, they were very original and creative. We also spent hours every night in the Billboards lounge listening to Jonathan and Emily playing piano - they were FANTSTIC. They seemed to be quietly competing with each other, something they tried to hide in a cloak of pretentious modesty but the underlying tension made the show that much better. I also liked the string/piano quintet that played in another lounge but my W doesn't share my interest in classical music so we didn't spend much time there. Compared to other ships I thought HAL did an overall better job.
Smaller than standard staterooms on other lines. Liked the bathroom better though.
Walked and snorkeled. The snorkeling was low quality but there in not much else to do.
Booked a Scuba dive with Aquamarine. Great dive, nice coral, small but very professional operation.