Firstly I would like to say that all the cast members did a great job in their respective roles. To me, no one felt lacking in any way.
Song Kang seems to be the perfect fit for the role. The charisma needed to be shown by the character Gu Won was perfectly depicted by him. His acting seemed great and emotions could be felt to the audience. Looking at him playing the character was really a delight.
Kim Yoo Jung proved how experienced actor she is. Couldn't have had a better female lead to accompany Song Kang. Do Hee's character was perfectly played by Kim Yoo Jung. All emotions she portrayed could be felt by heart.
Starting my review from the first 4 episodes: I was personally hooked on to the show from the first episode, the encounters between the leads and the later tragedies were perfectly fit in the episodes. The plot was made perfectly understandable from the start and the episodes and their storyline always made me want to know more about the story. All characters were shown in these starting episodes and had some screen time to each of them. The episodes had great comic lines and equal amount of other things going around to make the audience hooked upon the show. Most important thing that dramas should have is the power to keep the audience engaged in the starting episodes and this drama hit that note well.
Episodes 4-8: The main plot started to take place here. All the conspiracy in the drama can be seen unfolding in these episodes in the perfect pace. Each episode ending was made so perfect that would keep you on your toes for the whole week waiting for the next episodes. Gu Won characters develops quite a bit in this stage and shows different emotions in him. Both leads share a great chemistry in this part especially the comic timings in these episodes. Focus also starts mainly to finding the culprit and keeping Do Hee safe. The scenes were always some what predictable but the way they were shown and portrayed by the characters was what made a difference.
Episodes 8-12: The chemistry between the leads is best shown in this part. A perfect honeymoon phase starts that everyone would love to watch. The leads slowly get closer to finding the culprits step by step. Some parts of the past also start unfolding which makes the story interesting making one wonder how Gu Won ended up like this. Many questions remain unanswered during these episodes but the way the main leads carry the story was just great.
Episodes 12-16: The climax part of the drama was expected yet was able to bring some unexpected twists. All questions are answered well in these episodes. Unlike some dramas where everything is hurried up in the last episode, this drama did it well in maintaining an appropriate pace in unfolding the story. Nothing felt too fast or slow. The last episode will also leave one satisfied since nothing was left to be completed at the very end. All moments that a viewer would want are shown.

There were scenes in every episode that felt heart touching, gave you a smile and kept you wondering.
Madam Ju had a good impact till the end of the story even though one might feel in the early parts of the drama that she had less screen time.
Noh Suk Min was as expected and one could predict everything about him yet his portrayal kept me engaged.
Seok Hoon showed clear feelings since the start yet he was not predictable and one would question his intentions till quite some time throughout the drama. It was good to see his character was never made over clingy or interfering and was just perfect as a supporting person. His comic scenes with Gu Won were quite enjoyable.
Ga Young might have seemed a bit irritable at first but to be honest till the end she become a great person. Even her actions in the first half of the show were understandable after watching the whole show. Ga Young actually was a very determined person and I personally loved her character.
Do Hee's secretary and Park Bok Gyu were a gem considering the amount of laughter they gave to the audience. Their scenes with each other and their respective superiors were very cute and funny. Both showed equal love for their superiors. Bok Gyu's back story was quite some fun to watch. Both these characters played and important role in helping the main leads throughout their whole journey.
All office characters were prefect and a joy to watch. I could easily watch more of them on screen.
Do Hee's family had many issues yet their roles were portrayed well. Knowing more about them would have made the audience connect more to them, although I have no complains since the characters which got more screen time were actually the ones that should've been given in the first place.

The production of the drama seems great. The scenes and scenery shown are beautiful. Some scenes were edited so perfect that you would fall in love with the scene. The water scene on the small rocky beach type area was just perfect and I could've kept watching it.
The OST was just perfect. Can't get enough of 'Our night is more beautiful than day'. One of the best OST's of 2023 for me. The background music be it in the fight scenes or romantic scenes was on point and enhanced the beauty of the scenes.

In some parts it did feel like they are taking some time to show the obvious and felt that there could be some more story added to the show. Last episode might feel like a filler episode with cute scenes. The story was predictable at many points which made the cast the biggest reason to be hooked on to the show. The back story was shown twice at a point in the show which dragged an episode. Some characters could have been explained better.

I can honestly not find many shortcomings since I really liked the show although I do know it wasn't a perfect 10. Overall I would highly recommend it people who love to watch a cute bubbly romcom with a mystery storyline.

P.S. Feel free to tag me or message me if you want spoilers as I tend to avoid giving spoilers in my reviews.