When it comes to second seasons of anime, it's either hit or miss (mostly misses). However, I personally feel that this is a great second season.
The story picks up from where we left off and hints at things to come while also reestablishing the overarching plot and what has happened so far. The story is good, as it really does go off of what we know so far very well. However, coming from the first season, the story this time around is a bit more chaotic and all over the place. With the way the first season ended, it left me wondering what would the second season do. After watching this season, I still don't get why they did what they did in the first season. Some parts are done in order to introduce a new mechanic to the story while others are done merely to add controversy. After all this, the overall season was very boring somehow, despite so much going on all the time. Things get so overplayed this time around that you end up sort of despising certain elements that you wouldn't despise with the first season. In the end, coming from an amazing first season, the story this time around was a letdown.
The characters are all the same as before, but with a "twist". This "twist" being character aspects and behaviors being suddenly introduced with some of them. Especially Inaho. In the first season, he was all smarts which was an advantage for him. This time around, however, they seemed to want to do more with this and were willing to soil his character with OP smarts. The rest of the characters are all relying on him too much this time around as well, whether they are aware of it or not. Slaine's character, however, was better utilized this time around. Some characters were handled poorly while others were handled with care, which throws things off. Unfortunate, but this is the case.
The animation quality is still the same as the first season. Everything is well done, and the CGI is well utilized once again. Nothing much to say here other than amazing work.
Overall, a good second season but a bit of a letdown at the same time. I enjoyed every second of this anime, but I wish it was done better. If you're coming from the first season, have low expectations or you'll be disappointed as I have been.