The character development was, for lack of a better word, strange. As much as I love the concept, it wasn't executed too well. Characters seem to switch personality all of a sudden. Frenchie's relationship with Rose seemed very forced and pretty unrealistic. Frenchie's father coming back seemed super out of the blue and unnecessary, and completely took away from the "found family" concept the author seemed to be going for. The backstories tried to be realisticly but ended up feeling as if they were written for shock value and edginess only.
Lastly, Minerva destroying an entire school with her voice shattered the last piece of realism there was in the book. A total excuse to get the group out of their situation, and what happened afterwards was also very unrealistic. It would have been taken *much* more seriously.