Can't say I love Holly Black's worldbuilding, it feels like Geronimo Stilton en el Reino de la Fantasía on drugs, and that's not a compliment. It's unimaginative, it's overall boring. 

The character dynamics fail to charm as they should, which is a pity because the characters don't have much to say for themselves. 

This is really sad, because deep within (really deep within, so much that you'll have to dig until your fingers bleed) there was potential, as that very last line belied.