This is the patch featuring the least changes so far, due to the holiday season, but it is also part of what will eventually become a score system for daily/weekly seeds runs' leaderboards.
The Battle Stats screen allows you to check on the efficiency of your party and look for ways to optimize your units.
Right now, it only displays the amount of damage dealt, taken and the healing done by each unit in your party and in the wave, but that is subject to change.