This is somewhere between 4 and 5 stars for me. I had a lot of fun reading it - read the whole thing in one day. Good pacing, action, and I enjoy the characters. 
 When I look back at the trilogy as a whole, Leviathan is still hands down my favorite book of the three, but I like the resolution and the character progression. 
 For Deryn, yes secrets come out (but I'm not saying how!) and she learnes that there could be consequences for more than just herself. 
 For Alek, he's felt so much responisibility for the war (since it started with the deaths of his parents), that it's shaped most of his actions. He needs to figure out who his allies really are, and what his limits might be. 
 Down to the action and the gadgets - yep, those are still seamlessly interwoven into the story. The world in this series is just so rich, but it never felt overwhelming, like I was just reading blueprints. 
 The "bad guy" in this one is mad, yes, but like with many characters, his sense of right and wrong depends on your point of view. With a world at war, right and wrong are in a grey area. It does help shape our hero and heroine's actions though, and that's really the point here. 
 This is the end of the trilogy, and there is an end that I was satisfied with, although I'd be lying if I didn't mention how much I hope that we'll be treated to more from this world in the future. There are so many places it could go.