A great spot if you can deal with cold water and no aircon
We stayed here for 5 nights in November 11. It is a fantastic spot on the quiet side of the island. The staff were brilliant, food very good, and we really enjoyed our stay. However be aware you are staying in bungalows that are nice but don't have air con or a flash bathroom or even hot water. If you can handle this then you'll have a great holiday here. Yes food and alcohol maybe more expensive here than the mainland but you need to take into account that pretty much everything has to be shipped into the port then transferred again to the resort. Everything is still about the same price as the busy side of Phi Phi anyway.
I would recommend the half day trip to Phi Phi Leh island and if you like a hike go over the hill to the other side of the island and see how chaotic and noisy it would be to stay around Tonsai Bay.