I ending up reading a lot about this movie and Parsons' background out of nowhere. I really went down the rabbit hole. I watched all his "movies" on YouTube, to the extent you can call them that. Thankfully all the short clips have been gathered together into consecutive long videos now so you can watch the Backrooms videos and The Oldest View videos as if they were movies now.
I then went to see this movie in theaters last night. I thought it was fantastic. It's very much going to depend on your taste. Eerie, weird atmospheres are right up my alley but I could absolutely see many people finding it boring. The fact I had been deep diving on the lore and the YouTube content definitely made it much more enjoyable because I had a better understanding of Async than was provided in the movie.
I will say though that of the three "movies" (YouTube Backrooms, The Oldest View, and the Backrooms Film) I actually find The Oldest View to be the best pure "horror" experience. It's only about 45 minutes long and I won't ruin it for anyone but there's a two minute span in there where I was kind of losing my mind. Just a fantastic example of efficient world building and high tension.