Huge disappointment, the whole series was brilliant except for the last arc which was rushed and full of lazy writing/storytelling. I found the whole end of the world invasion as an easy plot device to end the manga fast, easy and add too many dumb shit/moments. The last arc I truly enjoyed was the Nurarihyon Alien mission, also the Italian mission was good.
Goodbye Gantz, I will never forget the epic train scene where the train gets sliced in half, the sex scenes, when Izumi disguises himself as a black man and kills almost 400 people in broad daylight, when you killed the main character in an epic way, oh and when Hoi Hoi (the panda) earned 40 points... goodbye.