Ok so this will be my first review ever on a drama after a few years of watching various drama myself, because I think the drama is worth for me to start reviewing from here. Also I base myself a lot on the comments before I decide whether or not to start watching a new drama so thought I should be a part of the community. First let me clear this up. Whether or not everyone here agrees, I still believe this drama is a must watch. An 8/10 for me. But for the sake of those who require an insight, give this review a further read.
Firstly the pros.
1) A semi-cliched but beautiful story line. As someone who gives a lot of attention to the plot, I give this drama a big thumbs up. The plot in this drama had a very full-filling and satisfactory development till the end, making sure all loose ends are tied up, giving justice to each and every character of the drama.
2) I don't think surgery would have been a part of Joseon during the time period in this drama, but there was a very good insight into the work arounds for the various instruments if used and such comparing them to the modern era. I loved watching the medical practices and various surgeries being performed in this show, each and every one of them. I can see the writers put in a lot of effort just by the pure detail of it, so if anyone thinks why is this a historical MBC drama, think no further, for it definitely can be said it is.
3)The romance was one of sacrifice and time spent apart but yet still kept sweet. I liked that they kept most of the romance aspects sweet and full-filling in the drama till the end and didn't introduce unnecessary second female leads to complicate it and take away the focus from the main plot.
4)Also the plot focused on the prejudices, and discrimination of classes of that time period very well, so might throw you on a learning curve on that one.
5) Agreed on this, the drama showed a great and patient character development. Especially loved the acting of the lead protagonist Mr. Jo Seung Woo. Also kudos to all the antagonistic characters of the drama, their acting was marvelous and very realistic.
5) As a musician myself, I can tell you this, great music!

Now for the cons

1) The lead protagonist in this story is basically GOD! He can do everything. His learning capability is a 100 times faster than everyone else. Not only this, he can fight villains away pretty much unscathed, figure out complicated political work arounds that even the king has no idea about sometimes. Basically the power, talent and focus on the lead was far too much to be believable most times. Also he is put through numerous atrocities through and through but still manages to remain not just good, but the kindest of angels. It was so exaggerated, the antagonist of the plot, the so called "Chief Physician" was basically useless as soon as he clashes with the protagonist. Like why would the kingdom place responsibility on a so called useless quack doctor, who can't heal anyone and only aims to stay in power. This was a little too much to be called "realistic" for my taste, and this coming from me who loves powerful protagonists.
2) The romance plot was great, but the chemistry between the protagonist and female lead honestly felt vague or non-existent to me. Also the female lead acting was just sad, reminds me of one of my cousins whom I cringe at for the way she speaks and carries herself. Worst kisser. You can see scripted effort being put in by the side characters to improve the image of the lead actress since she cannot do it herself. If your one like me though who likes to focus on plot aspect too and not just acting, you won't mind it too much.
4) Performing surgery requires that the place/room where its performed be extra clean and isolated, but in this drama, surgery was being performed practically anywhere and everywhere, without too much thought into it. I'd say the complications of this would probably be a teeny bit more than what's been shown on the drama, but then again, that's how fiction works. I'll leave it to any medical experts or doctors on board here to judge this.
3) The plot was predictable and cliched to an extent, but as I said before I did not mind that much.

All in all the effort of the cast and team was great, their hard work paid off. Even though there are aspects of this drama that I just didn't couldn't digest, it was one of the few long dramas that I binged to the end and did not stop and leave losing interest, as the plot kept me interested till the end, especially the medical, and surgical scenes of this drama. Give it a watch while you wait for other dramas or episodes to release.