This show is absolutely phenomenal because it's so real and relevant. Hands down the best anime I've ever seen. The characters aren't perfect: they're human. They get scared, sometimes their fear clouds their logic and they act frustratingly irrational, and no they don't always make the right decisions. Plans don't always work as you wanted them to and sometimes people die because someone didn't make the right choice despite the fact that they tried their best. Just like in real life there are situations were there isn't even a good option and but the characters are forced to make one regardless. The show mimic's the same unbiased cruelty that we see in everyday life. SNK doesn't just kill off random background grunts. The characters that die here have names attached to their faces and are people with family and friends just like the main cast. The fact that SNK forces to you associate a name with a face makes their deaths hit you harder because you realize how in reality death shows no discretion and anyone can die at any given time. Everyone's life is game.
This anime is also really relevant to modern day politics. You can see the whole 99% v.s. the 1% dilemma here. I'm paraphrasing the show here but one quote by Commander Pixis goes "The titans will be the instrument to [humanity's] demise not the cause". The show/manga often points out that humanity will be the reason for it's own demise and hints this largely due to political corruption.
POTENTIAL SPOILER: Eren points out in his trial (to those with political influence i.e. the rich and military authorities) that everyone is so interested in pushing their own selfish agenda that they are blind to what's at hand. We see this same dilemma today in various aspects of politics. Large corporations pay off politicians to create legislation in their favor even though it jeopardizes the rest of population's well-being and sometimes the world itself (as can be seen with the global warming issue).
It might not be so obvious in the first season (if you haven't read the manga) but the second season of SNK will DEFINITELY make this more obvious. I can go on and on about why SNK is amazing but I don't want to actually type it all out. Don't just take my word for it. Analyze the show and see how awesome it is for yourself. It's critically acclaimed for a reason.
