I personally felt the issue of erectile dysfunction was used for cheap jokes and as a way to grab attention. It belittled the problem, if anything.
The problems the main character had around feeling like a failure were different and tackled better though.
Why does Yoon Shi-yoon take these kind of roles, I wonder? He's played a couple where the character is the under dog; bullied, humiliated, the butt of jokes and with low self esteem and lacking in confidence.
I did like how this character didn't radically change though, in terms of his basic personality. Instead of transforming into a polar opposite, he accepted who he now is, what makes him happy and that those things should not be diminished or affected by the goals, aspirations and achievements of others.
Nowhere near my kind of drama though, sadly.