(First of all for the beginners I'd just list out the cantrasting parts of the story: It includes extreme voilence, blood and gore, but more than that it's called a dipression therapy for a reason; which is its mental traumatic scenes; but the actual story is no doubt great.)
The story is absolutely amazing; one of a kind piece of work, I loved the combination of elements like, biblical mythology+ Mecha+ psychological+ Gore+ Fluent action scenes+ unique animation style and full of brutal traumas plus it had a very major part conveying the message about true human connections,
I loved the whole series it was a blast, the music was great; but to be honest, its a lil bit hard to get a hold of the actual story.
Most of the time for the beginners including me; it was just like a show of gigantic Robots being driven by humans and fighting an alien race to protect humanity, but one needs to know that this ain't just it; there's a lot more to the story than expressed in the anime.
good luck to ya;
and yeah this is a depression therapy afterall.
enjoy!!