We learn nothing new about President Snow, he is a terrible human being and always has been. Constantly feeling he is owed more than he actually deserved, and makes comments like when things "smell like poverty".
The love interest was one note and your quintessential manic pixie dream which is a shame because if the story was about Lucy Gray I think it could have been a little more interesting.
This is also chalk full of Easter eggs, that are not subtle but instead Collins hits you repeatedly with a figurative "remember this" bat.
Since this is Suzanne Collins though the book is well written, and for anyone who remembers the Hunger Games knows she can craft a memorable and heart breaking story, this however is not it. This book didn't need to exist, I didn't need to be in Snows head and I am disappointed.