This was a solid second book for the series. I did like Steelheart more but that may just be personal preference.
I thought the trajectory of the characters was well plotted and timely. There really wasn't anything dragging the book down and it had a great pace.
I liked Megan better in the first book but she was still ok here. I think, by comparison, Regalia was less interesting for me than Steelheart was. He seemed to be a fuller character and Regalia seemed to be a side note to Prof and Tia.
I liked that David actually reconsidered his positions similarly to how a real person would have. Once faced with the reality of Epics that didn't fall into his narrow world-view he started to doubt and adjust his goals with the new information. Prof seemed so intent on utter destructions that it wasn't a great surprise where the book was headed for him.
The only real surprise for me was the reveal about Calamity itself. That adds another layer to the series that I am interested in seeing worked out in the next book.
All in all, a good effort. Much better than the typical second book in a series!