Okay first of all I love the first part, I was eagerly waiting for this one and it just totally disappointed me. It seems like the main writer wrote the first part, then he become sick and asked his pet to complete the second part as I don't think a person can write this much shits in one show. The vibe of two parts are completely different and second part is awful.

The ending is bad. Really bad and I will talk about it later, lets talk about other than the ending part first. So first we can see that the gang are doing their duty, they became pro in shooting and they finally become a team and doing great in killing spheres. They have a good shelter, a good amount of ammunition and food to survive. Everything seems fine. Right? To us but not to them. Maximum of them want to go back seoul to their home, because to them that place is safer. But in first part we got to know that in seoul there are more sphere, their patents went to shelter, so none's in their home! So why do they want to go back?? Just to get killed by sphere? May be. But after seeing so much things in front their eyes, after losing so many people how could they be this much childish? How?
Then a girl called Ha Na was telling lie to stay at their shelter and everyone was accepting that! that girl did not even guard the shelter properly, rather just did nothing, so my question is where is her consciousness? Is it even possible for a person who saw her classmates and platoon commander died while saving her to just do nothing and stay only at the shelter?? Really??
Dead of sung chool!! Sphere came and killed him! The sphere detectors were not well developed so it could not be able to detect the sphere, so it came and killed him, understandable. But then they just went back without attacking others! Why? Are sphere that much civilized! Or they kill one person at a time!! Others talked, moved even shouted in the same building, but the sphere did not attack them! LoL!
Na Ae Chol! OMG! She opened the prison without other's opinion despite knowing there are some deadly prisoners there! Okay! Humanity! But none even said a word to her! Like really! She disobeyed the team's decision and put everyone's life in danger, still she did not seem sorry or none told her a single thing! Huh! Everyone is just so great. But my question is not that. My question is the writer had only 4 episodes to complete the whole story. Does it really necessary to include this criminal angle? What does this angle mean to us? Nothing! This whole angle was for nothing but time wasting, boring and poorly written plot.
I even dont convinced with lie angle! It was also unnecessary . But as those babies love to stay at home, so they got angry with the clever ones and proved their dumbness. Understandable!
Now time for the mighty ending. Its bad! Its real bad. I am feeling sad, angry even disgusted after watching this. Just one thing i will say if I ever tell you to see duty after school, please forgive me for my ignorance. Dont waste your time and be happy.. I wish it was all Kimchi's dream. It would make more senses then this wedding.
I have ranted a lot in this review. This one is less of a review and more of my ranting session. Sorry for that. But i just cant sleep without writing all these. I am sure none will read this but if you do thank you.
Acting and background music were never the strong fort for this cast in this drama, story was. But as in this part, the story ruined everything so its useless to talk about acting and music.
Lastly, i am not trying to find plotholes or logic in fantasy drama. I am just trying to find the story which is necessary for making any drama.
Thank you.

PS: the pet completely forgot that, they had an ajhusshi who stayed with them in first season. So he could not even give him a closure or an endind in part 2.