GVR provided such a wonderful experience that it felt like we were actually living in Hawaii! The property is clean and everything was in working order (the A/C and washer/dryer were lifesavers). Just about everything we needed for 8 nights was provided (stocked kitchen pantry, paper towels, toilet paper, etc). The only things we needed to buy were condiments that required refrigeration (ketchup/hot sauce) for the few meals we prepared in the unit.
The only thing that bothered us about the stay isn't GVR's fault. The walls/ceiling of the unit don't have much in the way of sound-proofing so footsteps and children running around in the living room on the 2nd floor came through as loud booms rather than gentle knocks.
A note for transportation: GVR generously provides a mid-sized sedan (we got a Nissan Altima) but I would recommend getting good rental insurance and/or upgrading to something that rides higher off the ground (at your expense) because there are a lot of large potholes, rough entrances to parking lots, unpaved parking lots, and overzealous speed bumps in Kauai that can damage your rental.