We stayed 1 week and had a great time. The private pool was heaven for us and our kid. We also had a private parking at the beach, so that we did not have to walk the 15mins, which was very nice and unexpected (did not read that in the ad). In the first night 1 AC did not work but it was fixed promptly the next day and the support was very friendly. We also managed to loose the keys and were almost in trouble, as we noticed it at 8pm after which the agency's service hours end. However, we found another great solution, which we do not state here, but I think it should be told other guests as an emergency option. If not, be aware that in contrast to other providers you will be on your own after 8pm.
All in all we would come back, especially off-season because Chia was really crowded in July (similar to Costa Smeralda).