(I got an ARC of this book from the publisher through Edelweiss, in exchange for an honest review.)
Interesting setting, but ultimately the characters didn't keep me invested enough in the story. I wasn't sure at first why; in the end, I think it was because they were presented as badass, did have an etremely badass-y potential, yet didn't make enough use of this potential.
The good thing was that it made them vulnerable, more human, not the kind of characters who win all the time and tear through their enemies like there's no tomorrow. Ava had a painful past, was abused and betrayed, and this makes it quite ironical that she ended up as a hound, expected to show the loyalty that was never really shown to her when she was alive.
On the other hand, there were also several moments when they were too weak, didn't see through their enemies' ploys, ended up in dire situations because they hadn't been careful enough (though they knew they should have been)... Here's a Hellhound and a warlock who keep being on the wrong end of the stick, being the underdogs (pun intended), and it's not something I had expected from them. Obstacles and trials? Sure... Only not with such similar endings (character gets into problems, gets beaten up, blacks out, wakes up in an unknown room with someone who may or may not be an enemy...). This was all the more annoying with Ava, who's supposed to be close to a century old, and not just a budding Hellpuppy. Ava who keeps making wrong decision after wrong decision. You'd think she'd learn. (Also, akward sex scene out of nowhere.)
The setting itself was OK, with elements that could easily be used and developed later again: Leo's father and his thugs; what happened in Hell; whether Ava will be really free or not; the way boundaries aren't so well-defined when it comes to demons and angels, as being a meanie isn't limited to "the bad guys"... There's potential here as well, including vampires and shifters— not the most original I've ever seen, but not the cheesiest either. And necromancers. Shall I state once again how partial I am to necromancy?
Good ideas in general. My main beef with the book were the characters, whom I mostly found unremarkable, when they should have been.