Peter Ericson’s review published on Letterboxd :
"Room" epitomizes the power of cinema to have a big emotional impact on the viewer without any need for spectacle. This is a harrowing, heart-wrenching film that lingers in the mind for a long while after the end credits have rolled.
For seven years, Joy Newsome (Brie Larson) has been forced to live in a garden shed turned prison. She was kidnapped by a man only referred to as Old Nick (Sean Bridgers), who regularly delivers groceries and other necessary items. He also rapes Joy. He made her pregnant, and she gave birth to a son, Jack (Jacob Tremblay), who’s now five years old. Jack has never seen the outside world and has been told by his mother, whom he calls “Ma”, that Room is pretty much all there is. One day, Joy sees an opportunity for her and her son to regain their freedom, but it is very risky and presents a great challenge to Jack. Joy’s plan does, however, succeed (no, that’s actually not a spoiler). But life outside of Room turns out to be difficult for Joy and especially for Jack. Getting back their freedom was just the beginning.
Director Lenny Abrahamson and screenwriter Emma Donoghue (on whose novel the movie is based) tell an absorbing story and treat their characters and subject matter with the utmost delicacy and respect. The film portrays the mother–child relationship superbly and in an unadulterated way. Abrahamson makes it seem so easy: with small means, including the beautiful and minimalistic music score by Stephen Rennicks, he turns "Room" into a profoundly moving experience.
There is a wonderful sequence in which Jack experiences the outside world for the very first time. That sequence is brilliantly staged for maximum effect, and it’s also quite suspenseful.
For a brief period of time, I feared that the second half of the movie would enter familiar territory and introduce various clichés. But it didn’t. Not at all, in fact. The filmmakers deal with the aftermath of Joy and Jack’s incarceration so perceptively and so deftly so as to ensure that the second half is at least as fascinating as the first one.
Most scenes are composed to have some degree of claustrophobic feel to them, helped by Danny Cohen’s natural cinematography. It isn’t until the final shot that the sense of claustrophobia that has characterized the movie up to that point completely dissipates.
Being a character-driven piece, "Room" soars thanks to the positively mesmerizing performances by Brie Larson and Jacob Tremblay. Larson does a tremendous job of bringing the complexity of her character to the screen. And Tremblay is utterly convincing in a greatly demanding role for such a young actor, considering that the story is told mostly from Jack’s perspective. In supporting roles, Joan Allen as Nancy, William H. Macy as Robert, and Tom McCamus as Leo are all excellent.
"Room" covers a wide spectrum of emotions. There isn’t a single scene—not even a single moment—in the movie that doesn’t feel absolutely and grippingly real. The ending suggests that there is hope, after all, for Joy and Jack. After being emotionally drained, the viewer needs such a glimmer of hope. Needs it desperately.