At first, I didn't know what kind of story it was. Seeing Assassination Classroom didn't really entice me with any kind enthusiasm to read it. I thought it was your typical Shounen manga with lots and lots of meaningless battles and I also find that octopus teacher very weird just by how he looks but I thought I was prejudging it too harshly so I had a go at it.
And I really, really like it. I consider its plot unique, the comedy is very entertaining without being intellectually degrading and you sense a form of character development and bonding that's not found in many weekly Shounen Jump mangas.
It does sometimes drag by its feet, as usual for a manga published in weekly SJ but I feel that each chapter is a worthwhile event.