It is impossible for me to read, and thus review, this book without constantly thinking about my past. To keep it simple: Once upon a time I was deeply involved with someone with BPD. That person then spent a decade of their life focusing all their energy into making my own life a living hell. So yes, I'm very familiar with BPD, which meant I went into this book with quite a bit of experience, but also baggage. Because of this I could never trust Millie. At all. And I also strongly disliked her. Whenever she did something terrible she would then remind you she had BPD, which felt like disingenuous apologism to me. This technique might be effective for a lot of readers, but because I never trusted Millie it only make me dislike her more.
Rationally I know this is a pretty strong urban fantasy. The fey and magic were neat. There were some good ideas in here. I particularly liked Baker's description of what living with disability was like, both physical and mental. The voice was strong and distinct, and it was a quick read. The climactic scene was a muddled mess, but that felt like a stumble not a fall. It was a solid first novel.
Here's the thing, since I read for character, and I felt personally adversarial toward this imaginary person, I couldn't enjoy reading this book. For once I feel like it would be 100% accurate to say it's not the book it's me. If you're hunting for an urban fantasy with a fresh take, and want to read about a deeply flawed main character, maybe give this one a shot. If you have experience with the darker sides of BPD then go into this book knowing it might raise your hackles.