This was an exciting adventure book for young people. There's diversity in the characters. Emotion was well-done. The settings are spectacularly fleshed out. (I want to live in the cave house!)
If you cut down an early Harry Potter book to just the three of them on an adventure-of-purpose, you'd have the feel of this book. It reminded me a bit of my own youth, which is, perhaps, why I enjoyed it so much.