Ko'olau golds seem to greatly appeal to a few people, and not at all to a lot of people, in my experience.
They are VERY mellow strings, and I do not have the skills to bring out good tone or any sustain from these strings - when I play 'em, they sound dead as a doornail. They are also higher tension strings than I generally play.
If you play with your fingernails, like a classical player, you can get a broader tonal palette and more dynamics out of them. Or maybe if you are hard player, and/or have an instrument that needs to be toned down in brightness (in which case, I would use the Worth Brown's or maybe D'Addario's rather than the Ko'olau golds).
Words from a happy mediocre player...