My wife and I rented Karl and Rachel's studio for our ten day honeymoon getaway to Kauai and could not be happier. In addition to being in a great location (the North Shore ended up being our favorite part of the island; see below), the studio is quiet, clean, comfortable, and just the right size for a couple. Karl and Rachel were great to work with as we struggled to nail down our exact dates and kept changing things on them. We had the opportunity to meet Karl and Rachel when they were restocking the property and got to tour their 2-bedroom rental as well, which is also very nice and what we plan to rent when we come back with the kids. We spent quite a bit of time talking to them and they were kind enough to share their favorite places with us, as well as a lot of the island's history. The property description and photos provided here and on their main web site are thorough and accurate.
The area is fantastic and exactly what you'd expect from a Hawaiian getaway. Princeville and the town just west of it, Hanalei, are cute, quiet little towns with great food and shops, and the best beaches on the island are just a few minutes away. If you decide to stock the studio's full-size refrigerator, there is a supermarket with decent pricing in Princeville (for which Karl and Rachel provide a discount club card).
We were very pleased with the property and look forward to returning ASAP!