I really tried with Darling in the Franxx but I naturally lost interest. If you read the synopsis you could see why many have gravitated towards the series and why I would at least to attempt watch it:
The survivors of a catastrophic war against monsters cluster inside the fortress city Plantation and train youngsters to defend humanity by piloting large battle robots called Franxx.
So what was wrong with the series? First I’ll start with the good. The animation was top notch. And that was it. Much of the criticism of the series is that it drives too much from other mecha series like Evangelion and Gurran Lagann. I don’t think it’s the biggest problem the series has.
The obvious and silly fanservice. The pilots simulate the doggystyle sexual position, with the females bending over. The first few episodes lean heavily on weird sexual tropes. I only have the first few episodes to go on, but maybe the series had a more sophisticated plan in mind and I’ve missed it. The in your face sexuality has apparently force China to ban it.
Finally, I didn’t care for the mecha themselves. They were seemingly design after the female form, but it made them look to “cartoonish,” almost like large toys. In the first episodes the fighting aspect was clearly secondary to the emotional drama between the teens. If Darling in the Franxx wanted to hold on to some of the audience presenting more action could have done it.