It's two seasons of fun, laughing, learning, caring for the characters and getting tangled up in trying to figure out how this will all end. The jokes were really well written, making me crackle sometimes with enough life lessons thrown in which made it also a heartwarming show. You really do learn to care about Koro-Sensei and his students who are trying to kill him but are gaining life lessons I wish all kids could get from a good teacher.
There are twisted along the way which keep you wanting to get the next episode going.