First, we did enjoy our cruise. We like being at sea, the rocking motion and the noise of the waves at night.
Also we went with my wife's two sisters who were fun. We have done many cruises, somewhere in the teens and I am a Platinum member. I have done the Hawaii cruise 4 or 5 times now.
Pros: the gym was great for me. I found going at lunch time was best as there were few people there and I could get a pretty much uninterupted workout. The staff were especially pleasant and helpful. Embarkation took just a few minutes perhaps because we arrived latish, about 1 1/2 hours before sailing.
Negatives: the food was the worst I have had on any cruise. There were a number of strange culinary curiosities, one was peas with wilted lettuce cooked in, another with salmon balls in the soup, pea soup I think. The deserts were particularly disappointing some I only ate one or two bites.
The entertainment was not the quality I expect and, strangely, they would have two shows that looked good, one in the Vista lounge and an overlapping show in the Princess Theater. In the too small Vista lounge it was so crowded we had to sit so far to the side that we could not see the back half of the stage for a Princess troupe performance. It might have worked if they had a solo perfomer who could be at the front of the stage.
The internet cafe was terrible. Most of the expensive minutes going to waiting for pages to load even at logon.
Basically we enjoyed what we expect on any cruise line and had a good time in the ports. Not sure I would go Star Princess again unless it was an irresistible deal