Like the other reviews say, this place is just awesome. Robin is the friendliest, most welcoming host I've ever met and has endless entertaining stories to tell. The treehouse itself has a spectacular view of the vineyard, the mountains around Santa Cruz, and the ocean all the way to Monterey. I'll be recommending this to friends, and would love to come back some time.
If you stay, be sure to bring some warm clothes. We stayed in early April, and while the tent itself is heated and warm enough, you'll want to sit out on the deck which gets quite cold at night. Another tip is to bring a wide rimmed bottle. If you end up needing to pee in the night, it's really nice to be able to go in the bottle instead of getting dressed, climbing down the ladder in the cold and dark (though the ladder is partially lit at night), then walking to the house. Maybe not what you expect to read in an Airbnb review, but you'll be thanking me at 3am when it's 40 degrees outside.
Anyway, it was an amazing experience. Highly recommend.