Well, I'm disappointed. The second season change a lot of stuff. In the worst way. The art is changed, no more dark oppressive mood, now it look like the majority of the anime, more colourful and simple. The gore is gone. The action and the fights are boring and bad maded. The story takes place in a more trite and develop more slowly. In the first season happened a lot of thing while in this happened just like 2-3 and are boring. I'm hoping in the third season to come back to the old style/studio but i'm scared that cannot happen. Oh, did I mentioned that even the scientific parts are gone? No more explainetion about how certain animals or stuff works. Just a little info here and there but nothing of intresting..
I didn't understand the sword. Why and How?
But hey, they took us away everything cool from the first season but they give us humor! Boring out of content humor! Should be glad, do we? No.
If you want to know very quickly what can I say about the differences between the seasons, content for public speaking, all that I can say could be:
Season one 18+
Season two 13+