It's no secret I love Urban Fantasy as a genre. I'll pick up anything they write because really, they're pretty fantastic entertainment. That being said, Ilona Andrews (aka Ilona and Gordon Andrews) are at the top of my list of favourite authors. Both their Kate Daniels and the Edge series are really really fun reads - fun enough that my Mom likes them both, and she strongly dislikes Urban Fantasy as a rule. I was a little iffy on Gunmetal Magic admittedly. Set in the Kate Daniels world, it's main character is Andrea Nash, something that I was... unsure of. I don't want to imply that I can't handle change and it's scary and bad and oh god why is there a new character pov but you know. That.
That being said, the book was fabulous. Fun, clever, made me laugh pretty consistently throughout and had an impressive bit of character building for a one off novel. It didn't read like an "outside" canon book, it fit really well into the series and actually even gave a great break from the Kate/Curran focus. Solid addition to the series, and go pick it up. More to the point, pick up the whole series. I should probably be getting paid for this.