I've only watched the first 13 episodes, but I'm enjoying the series. There are a few places which might be hard to watch, as others have mentioned, because of violence toward women, but most of the episodes feel quite egalitarian to me. Some are completely non-violent and non-sexual, as well, so I feel that some reviewers are being a bit hyperbolic when they claim that a 'majority' are problematic. Several episodes show very strong female characters, which is great.
As for it not being for kids, it says this up-front. I can't understand how there are still people in the world who think that animation is automatically for children. It's just one way of creating art, no more or less 'serious' than any other.