Wilfred Lucas’s review published on Letterboxd:
Visually and sonically entrancing yet atmospherically dense, "Spencer" boasts brilliant performances and production values that elevate its slightly inconsistent "fable from a true tragedy” concept. The film captures the anxieties Princess Diana might have faced in a three-day Christmas family gathering with mesmerizing ingenuity. Pablo Larrain's film imagines the dialogues and the events that might have happened in real life.
Kristen Stewart's internal acting as Princess Diana is impeccable. Her mannerisms are on point. One gripe I have is that the writing and direction slightly limit Diana in a teary-eyed, breathy, and anxious delivery. Sally Hawkins, Sean Harris, and Timothy Spall provide unyielding supporting performances. Every scene Diana has with Maggie is touching, and every moment Diana shares with her two sons, William and Harry, is absolutely radiant.
The film can be described as a lush-looking psychological horror, and it indeed evokes uneasiness in the viewer. Jonny Greenwood, who is one of the best film scorers right now, composes a sweeping but mostly disconcerting jazzy score that helps induce that confinement and concealed madness. Claire Mathon's pastel-colored, washed-out cinematography has an underlying feeling of being trapped and longing for escape.
The writing is brimming with metaphors, visions, and symbolism, a number of which are noticeably heavy-handed. When the film enters its second half and as the scenes start to rely more on metaphorical conversations and illusions, it loses quite a bit of the sense of intrigue it has earlier on. Fortunately, there is a stunning montage of Diana's childhood to adulthood, and the stellar conclusion is surprisingly uplifting.