I really liked this one. I'm surprised at the bleh reaction from a lot of people. I loved snarky, sure of himself Wesley Crusher, I thought the threat was poetic if not especially scary, and Data was fascinating.
This whole trilogy felt like a novelization of the best three episodes from a whole TV season, in a really good way. Kept that TNG balance nicely of character piece / politics / sense-of-wonder in roughly equal parts (only leaving out the Planet Of The Week trope, which I'm thankful for), gave everyone a chance to shine or have some real development, lots of morality and contemplation of what it means to be human. Very TNG, very well done.
The only thing that ends up bothering me in the final analysis is the Breen. I know Mack loves them, but it would've felt a little more TNG-like if we'd had a classic TNG adversary; the second book felt like it could've just as easily been Star Trek: Typhon Pact: Silent Weapons. But the political element there is consistent with a lot of political episodes on TNG, and so in the end it's still a nice balance.
Great stuff. Not Destiny-great, but really solid.