This book's largest weaknesses are the slow development of the plot, which could have stood a lot more individual character development (particularly during the ridiculously long segments regarding Temeraire's training), and the blatantly Gary Stu-ish main characters. Lawrence's behavior is depicted as basically irreproachable, no matter how surly he gets, and-unsurprisingly-Temeraire turns out to be one of the rarest, smartest, bestest dragons in the world. Until, that is, it turns out that he is THE smartest rarest bestest dragon in the world! How shocking! Honestly, this reminds me a tad of McCaffrey's "The White Dragon", though at least Ruth had shortcomings.
Still, loving dragons as much as I do, I can't bring myself to dislike the book too much. A lot of thought has been put into the dragons and their various colorations, and species relationships. I only wish that this book has come out when I was 12, and could have appreciated it more fully; it definitely strikes me as more of a YA read.