Boy has it been a long time since I got hooked on an anime. My oh my Attack On Titan is a real wetdream. Soldiers zipping around like Spider-Man fighting monster ten times their size, using only agility to their advantage. This anime is wonderful on so many levels.
Story - The threat humanity faces is the Titans, a race of giant humans that came out of nowhere. Titans don't need to eat, fornicate, or defecate to survive; but they still eat humans ignoring any other animal. Humanity is fighting a losing battle against something they couldn't dream to beat. Humanity was pushed back into one big concentration of human civilization behind three massive and long walls that give the Great Wall of China penis envy. Humanity's only weapon is the 3DMG (3 Dimensional Maneuver Gear) which allows fit soldiers to quickly zip around in an attempt to strike the Titan in its only known weak spot, the back of its neck. It's a dark anime to be sure as we see people being crushed, eaten, and digested by Titans. (Titans don't defecate so they just puke enormous balls of gore)
Characters - The story spans five years giving ample time for character development. Each character is memorable in different ways. However characters die faster in Attack On Titan than in Game of Thrones. This show has a body count through the roof.
Music - Take the soundtracks for Dark Souls, Shadow of the Colossus, and Skyrim, toss them in a blender and you get...! A lot of broken discs. Take one listen to the theme above and get used to it. It's about that epic. Catchy too.