I watched and rated the series a 9.
Strangely, seeing it edited together and viewing in one sitting, made some aspects of the character's interactions a little perturbing.
I got that that Sang-ha possibly didn't want to share his troubles about the marathon with Jin-won before it, in case it affected his concentration, but directly after?...
Jin-won lacked empathy with Sang-ha and could be quite selfish, whilst the latter seemed to like him so much, he either overlooked that, or was ok with it.
The actors are very good, however, and portrayed their characters well.
Being a very light drama, the more realistic issues of their relationship, with the type of father Jin-won was intimated as having, couldn't be touched on, but it raised that question for me.
Life would be better if parents accepted their kids for who they are, but we know it's sadly not like that. Maybe one day gay relationships won't be viewed as different, lesser or wrong. We can only hope.