First of I got to say the ending is unique. it's just amazing,it triggered so many emotions at once, that I didn't know what to do.(it also influenced the story by 2 points)
I know the story is not an absolute 10/10 and the main idea isn't a new one either but the way they handled those problems was so good that I just forget them and fell in love.
As for the Characters,each one had a separated personality that sometimes changed over time which created a network of unique relationship's in the squad and every character had an own opinion to nearly every topic .(as for many other anime: they only include the MC's opinion and maybe another one)much effort put into that part even though most people don't even notice it.
At the very end I must say that it wasn't the best one I've seen but the ending alone makes it worth watching, that's why I gave 5 stars