I agree that I felt the Room was an exceptional showcase for attempting new ideas and trying to see what happens when they shove two or three things together.
The characters aren't spectacular, but the plot really is quite fascinating through its absurdity but very human stakes. There was also something great about the way this possession was festering and growing in Henry's apartment like a disease, and you saw in the locales you visited just how far and severe it could progress. The final explorable spaces were really great in that regard.
The way in which I felt the game was least successful was probably with the way it handled combat/items/exploration. The manner in which you explore Henry's apartment was alright, but the controls were less than stellar. I can't help but imagine the threat of the possessions and Walter's presence wouldn't have been less frightening were it not for the poor way to translate your inputs in trying to set a candle, run to another spot, and so forth. The variety in weapons and such were interesting, but I held on to those freaking golf clubs until the very end and still never used them. That might be a consequence of how I have been conditioned (either by games or myself) in handling items, but it felt as though they had too many options (which is in and of itself a bizarre thing to complain about). Combat, while better at times, felt too removed from the tone of the game. CHARGE UP YOUR ATTACKS just felt kind of like it didn't gel with the overall package.
That said, the places the game really shines it does so spectacularly. The tackling of subjects like voyeurism, the effects of living in these enclosed spaces where your own mind is the only place you can go, and all of Walter's mother issues was especially delightful. The creature and environment design had some real dandies, and the music is my second favorite soundtrack in the SH universe (behind SH2).
I really dislike how much it has gone from the black sheep of the SH family to this overly revered "THE LAST GREAT TEAM SILENT GAME" thing, primarily because I don't feel it is a good game. I think what SH4 does as a game is middling at best, but the art direction, ideas, and story are solid enough to warrant mention and some focused praise. I still have a soft spot for it, as it is such a unique beast, but I feel it has garnered a somewhat undeserved reputation in recent years because of an overcompensation to attack the western developed games.
I'm not sure where this last paragraph's train of thought is going, but it's just something I felt I wanted to express.
Regardless, glad to see people are still giving it a chance now-a-days, and I hope they continue to. I'm pleased to see you enjoyed your time with it, Dusk Golem, and I'm happy you were finally able to see it through to the end. : )