First of all, I love this drama and gave it a 8.5/10 ratings.
I refused to give it a perfect 10 because there were a few plotholes here and there, and also, the chemistry between Lee Jong Suk and Suzy was not up to my expectations, especially when they were kissing, it just doesn't feel right, I can't seem to feel their love and passion, almost to the extent where I feel like they're robots kissing on command.

Moving on to the pros, the casts were all significant in their own ways.  From the lead characters to the side characters, all of them played a part in making this drama memorable. Now, I do understand people have their own opinions and preferences, but to me, Suzy's acting has never been a problem for me, my first drama of her was Gu Family Book, and that was the drama that made me fall in love with her character, and she has never disappoint since then. Her acting in this drama was pretty flawless imo. Also, kudos to the villain, he did a great job in portraying his character, there were a lot of depths on his character, and it's worth it to keep an eye on him.

Some of the plots and scenes did exceed my expectations, but there are also some character developments which failed to meet my standards, one character in particular, Han Woo-tak. His character had so much potential and buildup, but sadly, it wasn't done well.

All in all, I love the storyline and the suspense. This drama is not perfect, but it's definitely worth watching, especially the comedy segments.