I liked Ezekiel's presence in the book. I wished we got to him sooner in Second Son. Hadiyah becoming Nobody is cool but out of left field. It's more I don't know her enough to care. Ironically I was the same about Jace when he was first announced so I'm confident Ridley could win me over. In hindsight Jace's era is plagued with sluggish pacing and a scattered focus.
The parent drama is harder to feel for. I could say it's a way for Ridley to explore Jace's tendency to run from his problems. But did we need to go this far back?
Plus Tanya complaining about Jace running away feels hollow because she sent him to boarding school. Unless she was talking about am incident afterwards?