At the time when I saw this anime I liked it only because of the Opening, honestly. Nagatoro was always a very boring character for me, Senpai is another one that I didn't like very much, his victim personality and always letting himself be humiliated by her, and the other characters weren't that great either. I'm surprised at how popular this anime has become, but I imagine it's because of the plot and characters that make it so different from most RomComs today.
Good review.