This is definitely one of the more interesting Silent Hills in terms of gameplay ideas, and there are a lot of great additions here. Honestly, if not for the last third of the game being an escort mission, I would probably like this game more than Silent Hill 3 or the first game. The first-person segments are really great. The apartment feels claustrophobic but interesting to look around in at the same time. I loved getting into a routine of going back to the apartment, healing, checking the windows and peepholes, checking the radio, and managing my inventory; and it's very disconcerting when that gets disrupted by hauntings later.
Speaking of inventory management, I also liked that addition to the normal SH gameplay. By mostly allowing you to return to the apartment really easily at almost any time, it avoids ever becoming tedious because of excessive backtracking. It also never really has the problem of not knowing what to bring and what not to, as it's usually pretty obvious what items will be required for puzzles, and even if you do miss something, again, it's easy to go back.
Definitely one of, if not the best thing this game has is the atmosphere and vibes. A lot of the cutscenes clearly have taken inspiration from found footage horror. You get these grainy shots of ghosts menacingly approaching Henry, and it's just extremely cool.
I also really liked the story of this game. I think it's even headier than other SH games, honestly. There's a lot of strange Freudian themes and imagery, and it's really fun to think about. Really, the only thing holding this game back is the escort mission. I know it's not technically required to keep Eileen from getting possessed, but it's only natural to want to help her. I don't know if this is a common experience or not, but personally, I kept constantly stressing and resetting the game every time Eileen was damaged more than a little bit. It made the last third of the game really tedious. Overall, though, I think the interesting things it has going for it outweigh that.