The story is very heart-warming. Lots of positive value on friendship, family, hard working and sportivity.
The reason that the rating suddenly went down is because on the 5th episodes there are some scenes that offended a lot of Indonesian, because the South Korean coach was complaining about the hotel not so good, the South Korean team had to train in a non aircon gym, and the Indonesian supporters being too loud, and the South Korean team won.
I am also Indonesian, but I think the scene was actually all right. I mean, coaches whining about not an ideal situation all the time. Supporters loud because we love our team, we want to give the best cheers to them.
So if you want to see something light and fun and sweet.. do give this series a try.