You can either be ecstatic or really disappointed which is why I am always hesitant if i only liked the anime.
I was surprised that I liked the second season more than the first.
I found that they did not repeat plot and the characters actually developed but, did not loose key personality traits.
They did sometimes switch to 3D animation but not to the point where it became a pain. The action sequences did improve. They added more detail but not to the point where you dont know where to look.
Overall, if you liked the first season you will love the second.
