This book is a lot of fun, what with the post-apocalyptic setting, dragons and marines (or rather the sorry remnants of what had been the Corps, they aren't nice guys), plus a bit of mystery and romance. The lead character Rain Mauri is tough, smart, and practical. Competent without being any kind of unreasonable super-heroine, which goes a long way to giving "reality" to her world.
I am confident a lot of reviewers will extol the virtues of MacLeod's clean writing and adept characterization, so I will just focus on one thing that for me made the book particularly enjoyable: It's sense of scale. With a lot of "fantastic" books, maybe even a majority, it seems that the fate of the whole world has to be constantly in the balance, or else the stakes don't seem high enough. That is not the case here. In this first volume of what promises to be a series, things are as simple as protecting the people of Point A from the people of Point B, and the narrative is still plenty engaging. There is room left for the stakes to get bigger and bigger as the series progresses, but that upping of the ante will be "earned," not a constant from the beginning. Honestly, I found it really refreshing, and it also brought a "reality" to a fictional world.
At about 45K words, Dragon Warrior is right on the edge of novella/novel length, and it is a fast and fun read.