a. I like to pretend that The Will of the Empress doesn't exist because I thought all the characters came off pretty terribly. She should have written this one first.
b. Not that this was great in any major way. It was a bit unfocused, and the characters just went from place to place because why? There wasn't the emotional impact you'd expect from events that supposedly leave Briar with PTSD, perhaps because the POV jumped quickly.
c. If she wants to write only about Rosethorn & Briar, ok. But I think the only way these books will become great is if the four actually get together again, and work together positively. That's what made the first series so good, and the second so disappointing. The Will of the Empress doesn't count.