Considering that this is a sequel (a fact I only discovered after I finished it), I supect the major development of Evelynee & Alleandre happened in the first book. Still, I think Alex did a wonderful job with this middle-volume. In Evelynee and Ally we have two very different, yet complimentary characters, both from very different worlds, who have made a deep and lasting connection. Their love is honest and sincere, and heartbreaking in the distance that later develops between them. Claire is a fantastic character as well - both visually and intellectually. I loved her development as another visible outsider who proves to be far more than anybody suspects.
My only issue with the book is that the supporting cast back in Atlantis seemed thin and under-developed. Again, they were likely established better in the first book, but I think some effort at reminding the reader and refreshing the characters would have been worth including.
Ironically, it's the 'normal' settings of The Sixth Age bar, the campus, the town, etc. that really establish the story here. Atlantis has an almost dream-like quality to it, and never really establishes itself as a solid, concrete setting for the action that takes place there. What we do see of it is amazing, and there are some very imaginative touches, but it didn't quite have that 'alien' or 'unnatural' feel to it that I expected.
Style-wise, the book was a little wordy in spots - some of the longer paragraphs could have benefited from a break - but the descriptive passages are very clear. The dialogue seemed a little stiltled early on, but either it became more familiar, or it developed as the book went on, because I found myself looking back at one point and realising it was now sounding natural. The cliffhanger at the end is definitely a disappointment, but it likely wouldn't have been quite so jarring if I'd realised this was part of a series.
Overall, a good book, and one that's made me want to check out Adeptus Major, the story that started it all.