Where this AVN shines
1) a compelling horror plot that has lots of mysteries. It's been a really long time since I last thought this much about a game, questioning my choices and relationships with different characters.
2) Even though the same stylistic device is used very often to advance the plot (X disappears, protagonist investigates, while Y disappears, this chain reaction plot device is probably the most used in this VN and while it can be quite annoying, it still works), this approach still kept me permanently in a state of suspense. I never knew where I stood and rejected sexual content just to protect certain characters. For me, it is a good sign for relationship building in an AVN plot if it motivates you to achieve goals that are not sexual in nature.
3) The atmosphere, including the set pieces but also the music, are well chosen. I would have liked the whispering of the first five minutes to have more meaning. But it seems that the developer quickly gave up on that.
4) I don't know of any VN where you can create your main character and the back story so beautifully yourself. It's really up to you to follow the plot here and make yourself a villain and two-faced asshole afterwards or make yourself more or less one of the victims in everything. The developer has gone to great lengths to give you agency here. In the end, that's what convinced me to give the fifth star, because it's really well done.
What could be improved
1) I think the plot could have done with toning down the pornographic elements and focusing more on the thriller. Sometimes there is sex at points where it just seems out of place and where it is not really explainable why a protagonist would rather have sex than do his job. Often you can object to that, but sometimes it feels like you're putting characters in danger. So you have immoral sex not because you are sexually aroused, but because the plot somehow suggests that it is the only way to protect someone. That seems very contrived to me and not necessarily believable. It kind of reminds you that you are playing porn with thriller elements when the game is doing such a good job in other situations to convince you it's a horror thriller that is not afraid to use sex as a plot device.
2) Day 6 is very convoluted. While up to that point the mystery unravels slowly, in Day 6 you are bombarded with new characters and the story is turned upside down several times. That makes it difficult to follow.
Beyond that, however, there is not much to criticise. Yes, the animations and character models are not at the top end of what is currently offered in the AVN scene. But who cares. I have already tried "The Guardian" by the same developer and I think Whispering Pines is the better game in every respect. At times it really feels like playing an interactive Stephen King book. And not many developers can do that. Actually, I can only think of one better horror AVN and it doesn't really have any sexual content.