Sky Ghosts: All for One was a thrilling ride from start to finish. Our heroine(s) kept giving me flashes of familiar characters: Buffy Summers, Faith (also from the Buffy series), River Tam, Beatrix Kiddo (aka "The Bride")...if you're a fan of ass-kicking female leads in the vein of heroes* like these, you may find what you're looking for in the character of Patricia, AKA Pain, and her sister Jane: a consummate sword-fighter with virtually no equal. 
 And yet, as impressive as Pain's martial prowess is, it's not her most fascinating trait. In this character, I also saw shades of other familiar characters, most notably Dr. Gregory House, M.D., if you'll allow me a minute to explain. Much like with the titular TV character, Engellmann's heroine has a noble and vulnerable core, defined by a deep-rooted desire to help that, like House, they view as a weakness or something to be hidden. Accordingly, Pain's true nature is wrapped under layers of sarcasm, feigned indifference, and even cruelty at times, and only the characters (and readers) willing to dig deep enough will find what lies beneath. 
 This is what allows the other characters to shine through, from her "to-the-death" sister Jane, to her friends among their order who came to respect Pain after being introduced to the reason behind her nickname, to those who are almost innately able to see past the gruff and grumpy nature she wears as a veil, knowing that there is gold at the heart without ever actually seeing it. Engellmann presents a heroine whose self-inflicted flaws can't even drive her friends away, and in fact just make them all the more willing to fight and die for her, just as she would do for them, no matter what she might say to their faces. 
 The combat scenes can be graphic, so your personal tastes may differ here, but there is one particular stretch of the book where there's fighting, then what seems to be an end, only to turn out to be a momentary lull before more fighting erupts. And then more, and then more. It's a thrilling roller coaster of adrenaline and emotion, to the point where the reader is left thinking, "When will they get 5 seconds to breathe?" Engellmann has captured the senses of urgency and desperation, and because of the way the reader is drawn to actually care about the protagonists, it's a thrill ride for both the actors and the audience. 
 Overall, Sky Ghosts is a great mixture of sword-fighting, humor, wit, sexual tension, and "imperfect romance" that brilliantly lets the readers feel like the characters, while supernatural, are fairly ordinary people underneath it all. We are left to care about the characters, and care what happens to them, and that keeps us turning pages - which means the book is a success. I am looking forward to future volumes in the series, especially after the ending. 
 * - Disclaimer: Faith and Beatrix Kiddo aren't exactly "heroes," but for the sake of argument....