Basically, I was thinking of a dialog box or sidebar option to write reviews about chapters read. It would just be a few sentences or more to remind users of what the chapter was about and what kind of impressions it left. It could be used when you quit reading a manga for some time and want to remember what was happening or (in some cases) why you liked it. It would pop up once you finish a chapter you haven't read before (Batoto already records this, as seen in the Follows section) and be viewable when looking over the ones you have.
I thought of this because while I was reading one of Kkotnim's neverending monotonous manhwa, I realized I was ranting silently. I know I could probably keep these thoughts either in my head or in a word document, but it would be nice to have it on the same site I read manga at and remember past feelings when I reread chapters.
I know there are forums and chapter discussions available, but I was considering more of the type of user-specific thing that is saved to the account, more personal.That said, this feature is not at all necessary. It would probably waste mega- to gigabytes of space. It's just an idea.