First of all, DAS had a wonderful storyline for S01, but sadly, I would say S02 was not good. I would recommend watching until Ep9. That would leave you a lot more satisfied than watching Ep10. Warning: further review contains spoilers. So Ep10 was dragged into the topic of Kook Young-Soo and how he literally killed his platoon members (4 members survived). The whole storyline of S02 hardly revolved around the spheres; it mostly revolved around the 2nd platoon. There were hardly any spheres in the 4 episodes of S02. The ending didn't do justice to the show. I would have been happy if I stopped at S01, but my curiosity about whether Mr. Lee is alive or not made me watch S02 (I watched all 4 episodes till 4:30 am). I don't know what I was expecting from S02, but whatever was released was not how I expected it to be. Where did Wonbin go? S01 ended with students being with Wonbin when the dynamite exploded, so definitely I would have expected Wonbin to be in S02. At least they should have shown what happened and why Wonbin was not with the platoon members. S02 had
so many inconsistency storyline ?. The S02 storyline was not something I waited for to watch, but the acting from the cast was top notch, especially from No Ae-Seol. Damn, I wanted to slap her here so badly for her naive behaviour, which means Lee Yeon nailed her character. I hope to watch more series or movies with his cast and a good storyline, obviously. 

Let's live, Let's Love and hope you enjoy your time by doing what you love ?