I expected a different setting when I read the summary for the book. I thought this would be a dystopian universe where people knew what the iron branding on her arm meant, and that's why Donna is ostracized. I was wrong, but the change in reality vs. my expectations didn't affect my enjoyment for this book. 
 I think the storyline is an interesting twist on the typical YA fantasy genre. The fairy element is still there, complete with the evil iron-fearing fae and insidious otherworldly creatures, but the inclusion of alchemy and secret orders give it a different feel than the usual teenager-meets-fairies trope. I'll have to admit, when I read about Donna having metal arms, and needing the Maker's services to repair something when she's in pain, I immediately thought Full Metal Alchemist. It is not a bad thing; it gave me plenty of topics to compare and contrast while I was reading this book. 
 Donna's character is most definitely not a Mary Sue. She is human, she makes mistakes, no emphasis whatsoever is placed on her appearance. Xan refers to her as a "pretty girl" but outside of that, I really can't picture what she looks like, or even her hair color. In a world full of books where the heroine constantly doesn't know how pretty she is, or has teal/purple/green/hazel/golden/rainbow-colored eyes, it's nice to have a normal looking heroine whose appearance is not referred to constantly throughout the book. 
 One thing I disliked about Donna is her inability to think some things through. She means well, always, but her decisions are not always for the greater good. In her defense, she does second-guess herself and understand that what she's doing might be good for her and her loved ones, but not the best to be made overall. It's like asking if you want your best friend to be killed in order to save 20 other people. There is a major moral dilemma there, and I'm glad Donna realizes that. I also like the fact that she understands that the monstrous creature that nearly killed her is not entirely at fault; it acts on another's command. I'm glad she has that sense of understanding and compassion. 
 Xan and Navin. Loved both of them. The love interest, Xan, is your typical loner, rich, handsome bad boy, but he's not a jerk. They author could have gone that direction and made him play hard to get or act like an asshole til the very bitter end, when he shows his true character as a golden-hearted angel in disguise, but no. Xan looks tough, but since the beginning, he is genuinely nice, kind, and extremely helpful. 
 Navin is the best friend ever, he's nice, helpful, and truly cares about Donna (although I don't understand why he's upset that Donna hid the truth from him, it is a pretty far stretch of the imagination, and I can't blame her for that). I am glad that Xan and Navin got along instead of going at it like two alpha males. And NO LOVE TRIANGLE. HURRAH! There is, of course, awkwardness between Xan and Navin. It is realistic, considering one guy is the best friend and the other is the love interest; I've been there myself, but overall, the relationship and dynamics between the three are well-done and not over-the-top. 
 I didn't like the characters of Simon Gaunt. He seems more like a caricature than a believable villain; there's no redeeming quality, and I can just about picture him sneaking around corners, with a pencil mustache, and cackling quietly and menacingly like a Disney villain. Not realistic at all. The ending and the pace of the story seems very rushed, also. The rushed deadline and the speed at which Donna accomplishes her target didn't seem realistic, considering how little time had passed before she even realizes that the Fae were reappearing on earth. Overall, though, this was a good, quick read, and an interesting story.