I'm just going to start with this: I did not like this movie. I can understand why some people would love it. So, it really just comes down to the individual. Objectively well made, just not for me.
Moving on: it's not a spoiler to mention that a major part of the story is the concept of a "younger self" in _How it Ends_. What is that? Well, it's literally a younger version of our lead character (Liza), who follows her around and acts as a sort of Jiminy Cricket; not too weird, huh? Well, it wouldn't be, but turns out other people have this too, and they're commonly invisible to everyone else, but since the world is ending, they can be seen. Does this have anything to do with the plot? No! It's just here for exposition and moving the story forward.
The next issue I had is that there's no real story here, it's just Liza walking around talking to people, which made this feel more like sketches rather than an actual movie... or even worse, a long therapy session.
Next: I hate the annoying Gen-Z-esque humor going on here, which is beyond bizarre since Zoe Lister-Jones is my age! In fact, almost everyone in the movie is in their 40s if not older. It's difficult to articulate, but the movie just comes across as made for/by spoiled children of rich parents.
Connected to this, what I was interpreting as Gen Z is actually more like annoying Californians. This is even more confusing: am I supposed to find this funny in an oh-isn't-this-so-kooky Portlandia way or is the movie's entire world the butt of the joke? Either way, I don't like it.
Finally: I was super offended by the objectification of a male character (Sal). He is shown, in a gross moment of the female gaze, in only a Speedo, including a close-up shot of his bulge. I'm obviously joking. I never get offended by anything. I just thought it was the perfect inverse of what third-wave feminists are always complaining about. I just don't see how noticing or enjoying a part of a human's body makes them an object... that is to say, no longer a human. People are dumb.
Too bad the planet isn't really about to be struck by a meteor. I wanna see the ground give way. I wanna watch it all go down.