Story:
Not starting as comedy in first half anymore, rather showing how main characters and their relationship were affected by what happened in 1st season, then resuming fights in second half.
We can see more of main characters and their development, skipping side characters & world introductions. Overally more consistent.
Animation:
Certainly better than 1st season. Effects are pretty good, though sometimes not fitting facial expressions still persist.
Sound:
Improved voice acting quality. Personally fell music in 2nd season more immersive.
Overall:
Good and interesting anime worth of watching, significantly improved over 1st season, though still suffers from short episodes.