Without adding too many spoilers, the series, overall, is well written and the actors are believable. Although many series created in South Korea might be a bit long, their new approaches to themes is really refreshing. So, I really enjoyed the series, One point leads to a reduced vote: some of the cases in the plot seem to be a bit unrealistic. Unless the laws in South Korea are really different from the law standards in western democracies, they would be not reaching court level. But this is not the problem of the series but the authors choice. And from other series written by him (like e.g. Pinocchio) he writes really good plots.
So, overall the series is really watchable.