I don't know why I continue reading this series. It must be the excellent narration provided by Gerald Doyle for the audiobooks. This book is way too long and not much really happens. There's no reason why the third book of this "trilogy" needed to be broken into two 850 page/30 hour books. Still, dragon warfare is good fodder for commuting -- it requires very little mental attention but is mostly entertaining. The ending of this book/series was pretty disappointing; after the final battle, the author then spent a huge amount of time tying up every single loose end and sending the characters off into the rest of their lives in mostly unsatisfying ways.
I wouldn't recommend starting this series, but if you've started it, you probably want to know how the final battle plays out since the villain is sufficiently interesting to be worth following. Unfortunately, you'll likely be disappointed with the way his defeat is finally brought about.