Jaime Grijalba’s review published on Letterboxd:
For the longest time I thought that I was being both artistically and emotionally distant to this film, but then towards the end, specially in the middle, once they've left the Room, I was feeling the emotional impact of everything that came before it and that wasn't being represented in the screen. I must say that I had the usual claims against this film and against all that was portrayed, about how it seemed to both demean and underplay the abuse of Ma, as well as the psychological damage that was done, but I was pleasantly surprised when it was quite the contrary, that you could find all that wasn't talked about in the silences and the eyes of Brie Larson, who I do think gives an amazing performance (but can't live up to the livelihood and wide-eyed spectacle of Blanchett/Mara in 'Carol'). I also felt that for some time it was doing nothing with its subject, that it was not doing so much, but when it achieved the emotional highs, they were felt, and specially in the relation between Jack and his grandmother, I could feel that it was all worth it.
But I do think that the director completely squandered the reveal of the world to Jack. A shame.