I never posted any reviews for any dramas before, even though I watched many many of them. I created this account just to post a review about this drama, so that people looking through the reviews decide to watch this drama as soon as possible.

Here is my tldr review:
This drama is a unique and refreshing piece of work. It's fun and amazingly paced which keeps the attention of the viewers from the start to the end. The story is not very unique but the pace of the drama and the brilliant acting of the casts makes this not so unique story a very unique experience. All the characters had their purpose and their development was properly done too. This drama is for those who like episodes with funny sweet and tense moments in a properly balanced way and want to feel the excitement they felt watching the first episode throughout the whole drama.

Now comes my in-depth rant:
Most of the "Good" K-dramas starts strong and fun but as if as an universal law they lose all their color and refreshing moments in the second half. The characters become sad empty shells of their vibrant past selves from the first few episodes. Even dramas with comedy tags become sad dramas as if everyone has a disease of sadness. The scenes become too intense without any proper breathing moments. The romance scenes become the same as other dramas. If you saw one you've seen them all. And the worst of all is the plague and disease of all dramas, the disease which infects even the best of the dramas, yes you are right, the flashback disease. The dramas become so pitiful at the second half that even the characters start seeing flashbacks of their great and glorious past. Now if you are one of those people who love to watch these sad intense flashback ridden dramas then that is up to you, you weirdos, see a doctor asap. But if you are one of my kind of people who can't stand these sad excuse of second halves that ruined so many great dramas and the flashback plague then this drama is for you.

This drama starts with great momentum and you will ride that momentum throughout the whole 20 episodes of this drama. I dare say it gets better the further you go. The characters become more fun each episode, the romance gets a bit more sweeter each episode , the story becomes a bit more intense each new episode and when the story is starting to get too intense a breath of fresh air will be given to you with very well placed comedy scenes. You will be start to feel sad at one moment but you will have to laugh hard at the next moment because of the sweet and funny interactions of the characters. Sadly the flashback disease got to this drama too. For all 20+ hours of drama time, there was less than 20 seconds of useless flashback in total, and honestly I can see why they used those flashbacks, so you won't even notice it that much. There were twists in the drama some were predictable some were unexpected. The story won't frustrate you too much, but it will also keep you wondering what comes next. Overall the story progressed beautifully.

The FL was amazing. If you like strong FL with "Don't F with me or I would F you up" attitude then you would love it. The FL was as ruthless in the last episode as she was in the first episode. The actress played the character of a proud male stuck in the body of a queen amazingly. The ML was strong with realistic problems and weaknesses. ML was a likable character with zero identity crisis. The villains were played well too. The supporting characters were as much part of the drama as the main leads. The characters and the brilliant casts who brought these characters to life made the drama a gem to watch.

The music wasn't the best part of the drama but it also wasn't bad. It had appropriate music in appropriate places. But the music wasn't something that you would usually want to listen to later.
The production quality was great, the costumes and the sets were high quality. The locations were beautiful. And the action scenes were nicely choreographed.

About the ending:
(Warning! Even though this contains no spoilers if you haven't watched the drama yet I would prefer you watch the drama first before reading this part. All you need to know is that from start to finish it was a great drama. But if you are the curious type and must know what I have to say about the ending, then by all means proceed.)
The ending seems to have sprung some resentments among the viewers, but I can assure you, even if the ending caused resentment to some it is in no way a bad ending. The ending had no flaw and no unfinished business was left. It was not a rushed ending. It was a thoroughly and properly done ending. At the end of the day not everybody will like every outcome and this ending is the classic example of that. The ending was in no way boring. It kept my attention the whole way as it kept on other episodes. So for me it was a good ending to a GREAT drama and I wouldn't ask for anything more from the ending.

This is my first review of any k-drama and is probably the last. And this review is a sign of my fondness for this drama. I hope they make more like it in the future.