James Haves’s review published on Letterboxd:
I showed this to my mother last night. We agreed it was a stunning piece of work, made by a genius, but I think something truly changed in me when I saw this for the first time, something I didn't notice.
Watching it again, I believe this is the apex. This is as far as it goes.
It's only an hour long. It mostly revolves around stick figures. It has a third person, storybook-esque narrator. And yet, despite the surface crudeness, this is one of the most complex, intricate, intelligent pieces of writing that I believe has ever been put to film.
I said that Outer Space was the personification of going insane. Well, It's Such a Beautiful Day is that as well, but so much more, and it's about going insane in a much less interesting way. It's not about everything burning and being destroyed as your entire perception of life crumbles around you in a blast of hellfire. It's about losing your grip on reality slowly and in the most human way.
Everyone is afraid of death. But somehow, when films like It's Such a Beautiful Day exist, maybe death seems a little less scary. Maybe death is the most inevitable part of life, and so being scared of that is totally pointless. If we accept that we're going to die, and that everyone we love could well die before us, maybe our time with them will be cherished even more.
I know that's how I felt. And that's how I think I was changed by a stickman named Bill.