Oh boy, this is going to be a tough one to talk about. I have very mixed, and somewhat polarized views of how this turns out, and as such, I'm struggling with whether or not I can offer a recommendation. The first five or six episodes are fantastic! After that, however, I really feel like the show peters out, begins to meander and run in place, and then kind of unravels in the end. Those first five or six episodes are so good, however, that I think I can recommend the series as a whole based on the strengths of its first half.
I can't discuss this show without getting into spoilers, so be warned that the further down you read, the more spoiler-y this will become.
A masterfully suspenseful start
Each of the first five or six episodes is told from the point of view of a different sibling in a family that is tormented by a summer spent in a haunted house. This structure creates a deeply textured and nuanced tapestry, in which each episodes recasts the events of the previous episodes in a new light. Giving each character his or her own episode provides us with a rich character study that helps us to understand each character's attitude when they all get together and the family drama gets rolling. All the while, the subtle supernatural elements create a building sense of intrigue as the mysteries surrounding Hill House, and the family's last night there, continue to mount and the plot continues to thicken.
Each of the first six episodes is told from the perspective of a different character.
I really love the camera work! Slow pans and zooms are used with excellent effect to draw out scenes and add tension and keep the scene mysterious. Sometimes, there's a creepy detail in the background. Other times, there's an ominous lack of anything creepy to see as the camera slowly pans from character to character across a room or down a hallway. In any genre other than horror, these labored camera movements would seem wasteful and pointless, but they really add to the atmosphere here.
The set design is also really great. The gothic Hill House provides an excellent and ominous set piece, but the other sets are also uncanny and unnerving in their own right, especially Shirley's funeral home. Around episode 6 or 7, I was really starting to struggle with reconciling the geometry of Hill House, and this is something that is paid off really well at the end of the series.
The geometry of Hill House becomes a source of unease as the series develops.
A meandering, incoherent ending
Unfortunately, the series faltered a bit for me after the sixth episode. At this point, all the characters are together in one place, and so no one character receives the focus of the narrative. The story starts to meander a bit here, while also running in place, as the intrigue that was so carefully crafted in the preceding episodes is squandered, new plot points and concepts are thrown at the audience, and old plot points and concepts just disappear.
The answers that The Haunting of Hill House eventually provide just didn't live up to the intrigue that was built. The early episodes set the stage for some big reveal, while the writers try to divert the audience's attention with red herrings about mental illness or hallucinations inflicted by exposure to black mold. The final episode tries to handwave all the mysteries that were built up with a few lines of expository dialogue here and there. What's set up is never paid off, and what's revealed feels like it was never properly set up.
The big reveal doesn't really live up to the intrigue that was built by the early episodes.
For example, we never get any real background about the ghosts who are haunting the house while the Crains were trying to flip it. The motivations of the Hills (why they are haunting the house) is never really clear. It's also never really made clear why they aren't happy as ghosts, like all the other characters are in the end. Do they chose to appear in their horrific and decrepit forms? Are they stuck that way? Does the house somehow control them?
Speaking of the house, it's motivations are also left unclear. It is said that the house wants to digest its occupants (in the Red Room). But to what end? Does it simply sustain itself off of the mere presence of people? Does it want their souls? Is it continuing to feed off of the trapped souls of the Hills, the Dudleys, and the Crains?
Why are there suddenly Vonnegut-like ("Vonnegutian"?) time travel elements thrown in?
Moving on
Then again, the big reveal isn't really the point here, so it doesn't really matter so much that it doesn't make sense. This isn't The Sixth Sense. The horror of this series isn't derived from ghosts or plot twists. The horror comes from watching this family that is so traumatized by its past that nobody can believe or trust each other. The horror is watching these people's lives fall apart as they completely fail to communicate with each other, as they constantly talk and yell past each other.
What does matter, however, is that the show's overall message is muddied by the clumsy ending. The whole message behind the show seems to be that these characters need to move on with their lives and stop dwelling on the past. They need to confront their trauma and move on. Yet this message is muddied by the sappy, happy ending that has everyone being reunited with their dead relatives in the house and living forever as happy ghosts. Are we supposed to feel happy for the dead Crains, or for the Dudleys, who are perpetually living in the past and refusing to move on? Isn't that completely antithetical to the other message about a family overcoming their pain, banding together, and putting their lives back together as they look to the future instead of dwelling on the past?
The ending is muddled by a part of the conclusion that seems antithetical to the message of the whole series.