Mr. DuLac’s review published on Letterboxd :
I am the ego man, goo goo ga choo.
If you're going to watch an animated musical featuring The Beatles it would probably help if you're a fan of their music. That's nothing unique to this film though, whether or not you like the music in any musical is going to effect your viewing experience.
The movie's characters and character designs are extremely charming and The Beatles themselves are constantly poking fun at themselves. There's a scene where Ringo ends up ejected from the Yellow Submarine and the group's first instinct is to figure out how to go on without him (Learn to sing trios) before Paul finally interjects with "Naw, let's save the poor devil".
The animation borrows from whatever the scene in question asks for. There's a lot of surrealism, pop art, rotoscope and of course traditional animation. Surprisingly this works on more then one level. On the surface a lot of what you'll see will seem like something straight out of a child's mind, but a lot of the characters have deeper influences that only adults will get.
Other then the music, the most enjoyable thing about the film is the dialogue. There isn't a single line in the film that is serious. Everyone speaks in puns and quirky responses. John is constantly comparing their situations to Einstein theories while Ringo struggles to find funny puns as the rest of the group groans at his attempts.
It's like a 1960s time-capsule but also one of the most unique animated films you'll ever see.