I watched START UP for three reasons; first, I like that Suzy chick, second, it was on trending for a long time (still is) and third, fuck you there is no third reason.

It is a nice story, really it is. All the characters were amazing and the OSTs were orgasm to ears.
The story being filled with passion for dreams, with romance and drama sprinkled perfectly on the top of it. The characters are lovable, especially the granny. Some characters were inspirational like the father, who quits his shit job to pursue his dreams. Then there were some cunt like characters, those who you want to bury in the deepest of the seven fucking hells. (the are necessary evil)

Though the centre of the whole story being, the three main characters. People might get confused as who was the fucking male lead in the first few episodes. Is it the Han boy, who wrote the letters, helps the female lead and was at the centre of everything. Or was it the Nam lad, who just got barges in later and steals the show away.
And I see people debating about the two male main leads. But for me, I don't give two fucks about how the Han was robbed by the Nam and bla-bla-bla.

Because the romance wasn't the main theme mfs, it was the dream. The passion. Seo Dal MI wants to be a successful CEO so her dad's dream could live through her. In Jae wants to prove her in the patriarch society that women can and will be great leaders. Nam Do San wants to be become his better self and unburden the title of "genius" others give him. Because he wants to be a confident decent man than a skull-cracked genius. Though Han doesn't have any dream, cause he is already successful, so he wants to help those who wants to make their dream come true. (fucking Genie)

So if you watch it for romance it is then just a mediocre shit. But if you see it for what it is, then it is worth watching.

It will make you wanna FOLLOW YOUR DREAM.