This is not a lengthy review, as other users already mentioned tons of great things about the series.
You can argue that other series' plots are way better than ITSAY's storyline. I mean, the story is somehow cliche - story of two man that are bestfriends who turn into enemies, back to bestfriends and being lovers at the end. So, what makes this series a topnotch for me? - IT'S THE OVERALL IMPACT. The plot is common, but the way they potray emotions, put hidden meanings, and execute the storyline make it stood out. This is a proof that a great storyline alone will not make sense if the execution isn't good.
I Told Sunset About You needs something, and that is an INTERNATIONAL RECOGNITION. With this series who gave us splendid acting, outstanding cinematography, great OSTs and very relatable content, we can therefore say that THE WORLD NEEDS TO SEE THIS DRAMA.