Being a resort, the prices are four or five times what you spend elsewhere, the food wasn't bad, but wasn't up to the standard we had experienced elsewhere in Thailand, and was at a much higher price. This is true of much of Railay, not just Sand Sea. There are cockroaches all over the path, if you leave shoes outside they will be filled with them - although none made it into the room!
The location is wonderful, the beaches are beautiful and in the resort you are on West Railay so get a beautiful view of the sunset. Air - conditioning is good and the room was clean, and exactly like the images. The staff were helpful, even recovering a mobile phone we had left in a taxi. It is an easy stroll, along a beautiful carst cave-lined path to Phra Nang bay, which is just stunning. Go early evening, when the daytrippers have left, and you'll be treated to mischievous monkeys descending to eat. There is a good range of excursions which pick up from the beach, or from the floating jetty at East Railay. All of the travel agents offer uniform prices, and uniformly better than you would get booking ahead. I'd highly reccommend kayaking at Ao Thalane and snorkelling on the Hong Islands. Make sure you don't miss the diamond cave, a few minutes walk from the resort, but not signposted anywhere!