Here are most of the problems I have with it.
The shot composition is mediocre at best, and uses way too much shot reverse shot. It's nothing but flat, uninteresting straight on angles.
Every aspect of the show is plagued with horrible inconsistencies. The animation is so inconstant and goes off model so often, every animator working on the show would have been fired had they been working on nearly any other show.
The usage of powers, abilities, and tools among the characters is more inconsistent than Generation 1 Transformers.
The tone is constantly shifting, often several times in a single episode. At one point, they main cast is faced with the literal end of the world but manage to still make time for goofy filler shenanigans.
And I haven't even gotten to the characters yet. Of which there are two I really don't like.
Lars is one of the most despicable, unlikable, intolerable, unforgivable, piece of trash characters I have ever seen in any cartoon. Every episode he appeared in prior to his redemption he acted like the absolute worse person, and yet every time the episode expects you to feel bad for him, and then what little development he may have gotten in his last episode is completely gone by the next one.
And Steven. Oh where do I begin with Steven. I absolutely hate his attitude on people. Every time a new gem shows up and tries to destroy the planet, he tries to give them a second chance because everyone deserves a chance for redemption, and deep down they're really a good person! But the moment any human character acts mildly unpleasant or rude to someone else, oh they can just go straight to the pit... Unless of course it's Lars.
And it doesn't help that he's shoehorned into every single episode. The Steven exclusive perspective the show has makes everything so restricted. Absolutely nothing can happen without Steven. Everything has to revolve around him like he's some special little snowflake and I hate it. Have an episode that focuses just on Peridot and Lapis, or the off colors. Let literally anyone else get some time in the spotlight without forcing Steven into it.
Edited for language by Prentice1215