We took this cruise because we've been to Hawaii before, but only to Oahu.
Pride of America lets you visit all the other islands without packing, unpacking, and going through TSA security endlessly as you fly from one island to another. That's a great advantage if you're willing to spend only a day or so on each island, and get a taste of each of them. Unfortunately, each island deserves more than a day.
Nevertheless, Pride of America is a good alternative to a quick and comfortable tour of the islands.