I haven't played it either, but I've watched a few YouTube playthroughs of it of varying lengths.
Yes, it's more of an interactive fiction experience than a "game" per se. Imagine it as something similar to Dear Esther, where you explore an environment -- in this case a creepy, deserted house -- read documents and journals, listen to narrative at various points, and attempt to work out what is happening, and reassemble the story.
There are no puzzles as such, just exploring and opening lots of cupboards and drawers to find papers and objects, and finding a way into locked rooms.
It's very atmospheric and emotional. If you explore thoroughly and take in everything, then the gameplay should last considerably longer than the hour or so that many YouTubers record.