Scott was a great guide who knows Kauai inside out. He showed us a breathtaking array of sights, left room for improvisation based upon our own tastes and what we wanted to do/see, and was very kind -- a wonderful person to spend the day with.
While this experience is on the pricy side, we both agreed that the private aspect of the tour was really worth it (as opposed to being on a bus with a lot of others). That's a significant part of what you're paying for here, so if you decide to do this, take advantage of the fact that you're able to tailor the tour to what you want to see, where you'd like to stop, etc. Highly recommended.