We had a fantastic time staying at Merris' place in Poipu! My wife and I were here for four nights as part of our honeymoon, and this wound up being an outstanding choice.
The location of the apartment was extremely nice. The Kiahuna Plantation has access to Kiahuna Beach and is just a stone's throw from Poipu Beach, making it super easy to just walk down in the the morning and also giving some other easily accessible options. The condo complex itself is beautiful, with well-kept gardens all over the place. It seemed that the bulk of people here were young families, though with a significant mix of couples and others as well. Finally, though it wasn't within walking distance to town, there's a fantastic coffee shop and bar right across the street that satisfied all our early-morning and late-night needs while we were here! It also is a pretty easy drive to both Waimea/Koke'e and the east coast of the island (~25 mins to Lihue), and we had no trouble doing a north shore day as well.
The apartment itself was lovely, perfectly clean, and came with fantastic amenities including great beach chairs and a cooler that we made plenty of use of. The lanai is lovely and looks over the Kiahuna Planatation's garden. The living room was huge and made for a great place to lounge around after a long day. Meanwhile, Merris was a fantastic host - she was extremely quick to respond to messages and was proactive in checking to make sure everything was going well and that we didn't need anything else.
Overall we had a fantastic stay at Merris' place, and would absolutely recommend staying here if you're looking for a place on Kauai's south shore!