This accomplished what it intended which was to allow a deeper glimpse into how both Day and June became who their characters showed promise of as young pre-teens. As other have pointed out one thing that stands out is of course the differences in their upbringings is so pronounce that it is really hard to not set Day up as the one who had it the hardest. Maybe in many respects but being bullied, belittled and left orphaned for June was as traumatic as the hand-to-mouth existence that Day had to deal with for many years.
I could have skipped reading this easily as can anyone else who has already read the trilogies full length books, for those who have not it will help put the characters in perspective a bit better before reading book 1, Legend
which finally read back in August of 2014 and got me hooked.