I'd recommend playing Yume Nikki instead or watching a playthrough of this.

I've waited for OMORI for a long time without knowing the controversy, just based on the trailers alone. I'm glad I played it but I can't recommend it to anyone else, just watch a playthrough. The dream world segments (which most of its marketing revolved around) are slightly lackluster. While it is in part intentional, it's overshadowed by the quality of the real-world segments which take FOREVER to get to. It has a lovely story with completely abhorrent pacing. While I do feel it handled its sensitive material decently, segments drag on for way too long, the dialogue is slow which is painful if you want to replay to get the other achievements. While there are some genuinely unnerving moments and some interesting little details to analyze, I wouldn't classify this as horror. Ironically the moments that are scary are a lot more subtle as opposed to the poster scenes the game tries to parade. Combat has a decent system but it's still relatively slow. With monster designs and some dreamworld sequences being... well bland and the build-up to important events being so slow OMORI easily felt tedious to play at times. I won't deny the charm oozing from OMORI, but it has some glaring flaws.

OMORI is praised for its art and plot often, which I agree with wholly but as a game, it's very prone to feeling static, so it doesn't wholly feel worth its price or time. I myself bawled my eyes out but it's a story that's enjoyed moreso for long-time RPG Maker fans. OMORI's plot certainly endeared greatly to me, and I do feel it rewards exploration, but it feels like such an unneccessarily long timesink. I'd suggest watching a playthrough for the story or playing Yume Nikki which is the poster example of well-executed dream-based games.