Portrait of a Lady on Fire is exquisite in the way that love is in real life. It hurts, then it feels so good. Céline Sciamma takes her time telling her story, which perfectly matches the gradual process by which the two main characters fall in love. The film smolders, and, as Mick LaSalle wrote, "The last time I wanted two people to kiss this much, I was one of the people."
Comparisons have been drawn between this film and Blue Is the Warmest Color, and it's understandable, although much of the discussion seems to revolve around picking one or the other as "better". Sciamma addressed this point:
We can absolutely love both films. We do not live up to the exciting nature of this moment if we start reducing everything to questions of ‘good or not good; moral or immoral; voyeur or not voyeur,’ that’s not the point. The key is to understand what animates such images, and what they seek to impart.
The films do make for instructive examples of the differences between the male and female gaze. And "gaze" is the proper term for Portrait of a Lady on Fire, for much of the relationship between the two women is shown in how they look at each other. Noémie Merlant and Adèle Haenel as a painter and her reluctant subject are perfectly matched, and both deliver perfect performances. Sciamma won Best Screenplay at Cannes, but the film relies on Merlant and Haenel. Backed by Sciamma's direction, the two actors draw us into their story. Luàna Bajrami is also excellent in a lesser but important role.
Portrait of a Lady on Fire looks great, as well, with cinematographer Claire Mathon making the most of what in many cases are scenes lit by candlelight.
Some of the best moments are almost wordless, including a remarkable final shot that stays with you long after the movie is over. And Sciamma uses music sparingly, which adds to the impact when it does occur, most notably in this, which I think is the best scene among so many great ones in the movie:
They are singing "non possunt fugere", Latin for "They cannot escape".
Simply put, Portrait of a Lady on Fire is an excellent movie in every way. #193 on the They Shoot Pictures, Don't They list of the top 1000 films of all time.
(Here is a letterboxd list of Film Fatales movies.)