Everyone seems to love this book. I don't.
It's ok. There's a nice section where the prince makes friends with a fox. I liked that part! But I didn't understand what message the book was trying to tell me. "Don't become an adult" maybe? Possibly "adults are boring and care about stupid things?" There's definitely an anti-adult sentiment, but that's not particularly actionable.
The book argues these points through a bunch of caricatures --- there's a king who "rules" nobody, and a banker who "owns" the universe. I guess the point is that believing something doesn't make it so? Or it's a bad allegory for "you also need other people?" Or something. In short, the storytelling is muddled, and the rest of it isn't charming enough to make up for it.
I'm not sure it's the book's fault, but my copy had some egregious english grammar. Maybe it was a bad translation, or a garbled ebook or something, but it was enough to frequently break my suspension of disbelief.