My 5yo and 7yo were enthralled. Likewise my wife and I. It's a lovely story filled with subtlety and nuance. It's not, however, G.I. Joe. Which it feels like the reviewer was looking for.

"It effectively establishes the world around the lead character but it could easily accomplish the same in less time" is straight gibberish - as if the point of doing things in film and television was to do them in less time.