I'm extremely picky about talking animal stories. I loved Watership Down as a kid - and few match up.
Lupus Rex doesn't - quite - I prefer my talking animals to less closely resemble oddly-shaped humans and more closely resemble animals who happen to talk. That said, Cash produces a well written tale that is both suitable for children and enjoyable by adults. The characters are fairly lightly developed - it's a kids' book after all - but different from each other and sympathetic. It also has the charm of being an underdog story. Out of all the species he could have chosen, Cash makes quails the heroes.
It does fall into the "prey vs. predator" trope to a point - and then mildly subverts it. A couple of things irritated me (king snakes eat other snakes, so why are they allied with them?) but, for the most part, this is a well written, if simple story about how might doesn't always equal right. He does frustratingly malign wolves, but that's another matter.
Copy received at World Fantasy Con.