Gui’s review published on Letterboxd:
I won't compare It's Such a Beautiful Day with any of Don Hertzfeldt's previous works, nor with any animation films that have been considered great or classics. For this 1 hour film is in a league of its own. It really is able to surprise you the most, combining such different aspects that you would never expect to be put together. Never has an animation film succeeded in mixing (hand-made!) animated figures with actual real film, yet this one does so harmoniously. Never has the medium utilized musical classics like Smetana, Wagner, Chopin so perfectly. Never have you felt such interest and humanity for a stick figure like in this. Never have you experience such an elaborate, existential, realistic story about a stick figure in any animated feature. Never have you really seen something quite like this masterpiece.
Because Hertzfeldt creates such a perfectly imperfect world, filled with insecurities, fears and complicated relationships. It's so realistic and yet so fantastical, and funny and sad, really funny and really sad, simply so (in)credible. And so time flashes by as you see a film that could stand as a philosophy, as a work of art, as a technical marvel and as a personal voyage.