This anime is actually really good and really well-developed. I like how the storyline is progressing so far, but I have not read the manga. However, so far there are 24 episodes. I'm glad to hear you like it as well :)

Attack on Titan.

http://en.wikipedia.org/wiki/Attack_on_Titan

This comic and animation is the most popular in Japan right now. I also really like it and can't wait for the next episode.

I wrote some points.

-There are 11 comics and 22 episodes.

- There is a novel and a game.

-Human vs titan is the main story.

-World is occupied(conquered) by titans.
Titans are very big and strong. And we do not know how many titans there are in this world.


- Mankind lives within the wall because there are titans in outside. Mankind live in a very small area.

-Attack on Titan is a dark story according to wikipedia.
I agree. This book also appeared in Shonen magazine. Not Adult, but Young adult magazine. I suppose this is very dark(sad) story for boys. 


I thought, "Why is this very dark and sad story so popular in Japan?"

I suppose(very personal opinion)


-Mankind works together.

After 3,11(Earthquake in Japan 2011) , the Japanese realized how important cooperation is.
I suppose cooperation is big theme in this story. So this story appeals to the Japanese.



-Titans are a symbol of a difficult problem

We were faced with a very difficult problem in 3.11. And There are still many difficult(hard) problems in this world.
We try to solve difficult problems in real world. Just like the comic characters try to do something about the Titan in story. We see something in it.

There are difficult problems in real world like defeating(beating)titans.

Sorry I can't explain it clearly.




It is dark and sad story
But if you enjoy Attack to the titan,I am glad.