Well I liked it much more than I expected. Saito Nagisa really stand out here (in good way). It can seem as a plot is something easy but actually it contains many hard topics and age content is actually right.
If you like kdrama , you have to keep in mind that japanese acting style is different (in most of their production) so it can be annoying for some people.
Note: there is also a second season (althought I have not seen it yet)