This show definitely has potential, but that's about all it really has.
First episode was a snooze-fest for the most part. It was interesting in the first portion, where Darby, the main character, was "reading" her book to the public. The story she was reading was not particularly good, but it was good enough, as a hook, since it showed bits and pieces of a very important relationship to her. This kept me going.
But then we had a very long segment of Darby being invited to a rich man's house, the travel there and slow introduction of most (if not all) other characters. It was excruciating. This approach to character introductions can work in a book, where you can share inner thoughts of the character, and thus establish not only the stating point for the characters being introduced, but also perception of those character by the main character. Or if you are using third-person you can establish some ground for inter-character relationships. In a TV show (or movie for that matter) it does not work that well. It can work only if you do rapid-fire introductions like "Lock, Stock and Two Smoking Barrels" or "Smoking Aces".
Nevertheless I was curious to see how they would unfold the mystery, which, probably will have a very predictable end, so I watch the 2nd episode. That one was markedly better, because there was no a bit more progression. I could even say that I enjoyed it, if I forget about some tech-nonsense.
Third episode, though... It had even more tech-nonsense, and it seemingly slowed down again, with even more exposition shots that were not brining anything to the table. And the end of the episode was also quite predictable, which is not that good for a murder mystery.
You seemingly have the needed components for a good show: remote "castle", multiple people with their own agendas and mistrust of each other, some barely-hidden secrets, that may be leading you astray... The overall atmosphere is also good, the shots are good, but..
I could not believe that I am looking at smart people. And it's not just the tech-nonsense. They were just shallow, uninteresting, and did not "feel" smart. Like Darby: she is supposedly very smart, she is not only a sleuth, but also a hacker, but the show does not really show her doing anything smart: just making conclusions out of some information she found and that's it. Yes, that's arguably a skill in itself, but not the way it's portrayed.
Another interesting episode, that makes little sense, but shows how pointless and uninspiring the show is: Darby dyeing her hair in this "castle". Firstly, I am unsure where she got the dye: did she bring it with her? Why? Was it somewhere in the "castle"? Why? Secondly, why would she decide to use it out of nowhere? I mean, if she brough it with her, maybe she planned to dye her hair, but... Why could not she do that before the trip? Thirdly, the way she applied the dye and the way her hair looked afterwards did not match, I do not think it would be an easy feat to apply it like that by yourself on yourself.
So, I do not recommend this one, after all. I tried to like it, but it's just not a good execution. A lot of reviewers say, that this is better than "The OA", but I think "The OA" did not try to be serious when doing weird and nonsensical stuff. It worked better there, because it was a show about weird things, essentially. Here it's just half-assed effort.