Bitter's story is both tragic and heroic.  It definitely takes the hero's journey and turns it on its head.  Bitter is a character you cheer for, hope for, cry for.  She is guarded for good reason but holds power of which even she is not aware. 
 This book drew me in as quickly as PET did.  Having PET as background information made some things clearer quickly that would leave new readers to the series in suspense longer.  I wasn't mad at this at all because we got to see all the things leading up to PET and I find back story amazing!
The writing was deep and beautiful.  There are so many correlations to our current world, that made this fictional world even more relevant.
This book felt as if it was written for an older audience than PET, but 100% loved it!

I liked this a lot, but it suffered a bit from inevitably being compared to Pet, which I loved. The writing style in Bitter is a little more grounded, a kind of standard YA writing where the lessons in the text are stated outright. Because this is set in pre (and during) revolution Lucille there are more real-world parallels. Some of these worked for me and some didn't. I liked the characters and the basic outline of the story but things got a bit muddled toward the end for me.