We had a great stay at Koh Tao Cabana. It is a beautiful place with lots of green, nature and direct access to the beach and a good pool. The breakfast menu and buffet was sufficient for us, choice of pancakes, eggs, fruit, etc.
The staff was mostly really friendly, some of them less but only a few that we noticed.
Our tree top house was quite some walking and climbing, but we were okay with that. We were all the way at the back, probably because we asked for a silent room. We did not hear any music from the bars as I read in the reviews. The scooter rental was also very convenient and you do need a scooter to go to the rest of the island. The road to the hotel was good, since I also noticed for some other resort further (Dusit) the road gets very steep and gaps in the road.
The food menu was okay. We ordered pizza margarita, but that was not what we expected and the town is close, so we mostly went out for food.
The water bottles and mini bar were very convenient and supplied every day.
I had doubts about the bathroom, since it looks outdoors. It technically is, but they closed it down so there were almost none insects. Expect a huge spider on our last evening. The reception was not 24/7, so we needed to take care of the problem ourselves.