PROS
-Epic Storyline
-Awesome action scenes
-Shounen main character tropes demolition of a protagonist. Epic supporting characters like Levi, Armin, Jean and Erwin.
-Excellent world building and mysterious atmosphere
-You never know what is gonna happen next
-Gory
CONS
-Sometimes slow pace
-Many characters die before being well developed, while others feel like wasted potential (Mikasa)
-Early chapters are not very well drawn

Overall: Attack on Titan is an epic manga that gives you the chills every single time someone screams "Change to 3DMG". There is a good reason why it is such a popular manga both in and outside of Japan. It is an excellent manga if you are starting to read manga, since it shows people that manga is not only for children. The slow pace might turn off some people, but it pays off with nice character development and immense action scenes that will leave you craving for more.