The second season has parallels with the first, but the cells are more prominent when they were more of a side note in the first season. Not just Yumi's cells but all the cells that appear. They provide the most comedy in the second season whereas Wung was the source of it in the first. Personally, I prefer season 1 but season 2 is deeper emotionally.
I've always thought the overall story is more about Yumi's bittersweet relationship with Wung, which is a much more interesting and emotionally packed story arc. I've always hated the going out, breaking up and getting back together storyline which has become a cliché (boring) and it happens here which is why I prefer the Yumi-Wung storyline.
At the very least the show exposes human imperfections and their decision-making driven by these imperfections. Yumi's hypocrisy, Wung's inability to swallow his pride and BaBi's creepy smile and sociopathic tendencies, and the latter made me worried for Yumi's future had she ended up marrying him. That's because Babi's daddy issues would have been exposed even more and his sociopathic tendencies will manifest into domestic violence and infidelity, but let's not go there. Let's be honest, Babi has been creeping around Yumi since the beginning and pounced on his prey the moment Wung was out of the picture; he mentions he doesn't get on with his father which hasn't been fully explored, and they haven't shown enough of what really happened between Babi and Da Eun. There is no way he didn't dip his bulgogi in her gochujang.
In the end, I hope they all end up with who they deserve. Babi doesn't deserve Yumi and Yumi doesn't deserve Wung. The series has an open ending so a potential for a third season which I would gladly welcome, but wouldn't mind if it ended that way coz that's how life is; there is no happy or sad ending, it just goes on until death.