It's crazy that this movie exists, but unfortunately, I think I like the ideas in it more than I like actually watching it.
Its strengths are many. There's great vocal performances (James Gandolfini and Catherine O'Hara standout), it has visual style, its score feels very specific (I don't like this music, but I admire that it has personality), and it's sensitive to the loneliness and existential fears of childhood.
But ultimately, it all wears a little thin. If 20~ min were cut (maybe the owls and Carol's model fantasy land thing, for starters), this movie would work better.
Also, the scene where Max hides from Carol in KW's belly has stuck with me since I first saw it nearly 10 years ago. It has Oedipal-eque psychological weight, but is depicted through a fascinating, surrealist lens. Hits you right in the head and the heart.