This is the first dragon book of hers that I gave less than 5 or 4 stars to. I don't think it's a stand-alone book. Heck, I've read them all and I was still confused by who did what when. It's a tough call about how much backstory to toss into each book in a series and I think she under-did it.
Temeraire seems to have lost some of his intelligence and love of learning--and he's caught in the whole competition with other dragons to the point of dullness. He'd matured so much through the first couple of books and now he's apparently done.
Plus Laurence's responses are barely visible. I know these are stories of battles, intrigue etc, but there was always enough emotion to keep me caring about the characters. Laurence finds out that one of his best friends is an invert (a great name for it--new to me) and he doesn't even flinch or consider the matter? Sure it's been a long time since he blushed at the sight of Catherine in trousers, but the whole contrast of his upbringing to this strange new world was a lot of fun. That couldn't keep up (the world isn't new any longer) and he just seems weary.
I suppose if you enjoy books like Lord of the Rings, this lack of deep POV won't bug you.
The plot was clever enough, though it didn't have a story arc and no one was entirely different at the end as they were at the beginning. Gong Su is the only one who's significantly changed and he hasn't really changed, just our perception of him. (Although I suppose Riley counts as "significantly changed" too.)
Will I still buy the books? Yup, and I'll be looking forward to the next as well.