It looks like it has been a while since anyone has reviewed this one and I felt the need to put it out there, in this time of summer self-quarantine, when we’re all avidly looking for something to keep our interest. This does that, in spades.
It’s lighthearted without being ridiculous, has serious moments without weighing you down, and still manages to grab you and make you think with ideologically challenging questions. So without further ado...

Reasons to watch:

There’s a decent plot. One we’ve seen, of course, sure. But it follows it pretty faithfully, and doesn’t forget what it’s doing halfway through. That alone feels rare nowadays. It may be silly occasionally, but it’s not insulting. It can actually be pretty clever. My favorite thought provoking line: “Are you aware that with passion comes responsibility?”

The acting. This has an insanely all-star cast, with the actors we love now in the roles that pretty much started them on their path to fame. The performances are brilliant, to say the very least. There is an air of the three musketeers- adding in a female D’Artagnan, naturally- about the quartet. Especially if you can see Porthos taking on shades of the Scarlet Pimpernel, and Aramis becoming Zorro. Add in an angsty Athos being unwillingly attracted to D’Artagnan (who just looks at him with dewy, loving eyes and emotionally slays him), and the Scarlet Pimpernel chasing Zorro with a playfully lusty grin, and that’s basically this show. I hope I didn’t confuse you with my analogies. :) But if you know the iconic characters I’m talking about, you will totally get it when you watch this show.

The second leads. Ok yeah I mentioned them already. BUT. In case I haven’t convinced you yet… the two men literally have the entire spectrum covered for anyone who likes men. (I worded that carefully.)
Take one man that stimulates most of the world intellectually, and then toss him in a role that is a walking dose of sexual pheromones. Then make him all hot and sweaty for a quarter of his scenes. (Raises eyebrow.) If you are still breathing, I will not understand how you could not be attracted to Yoo Ah In, especially in this.
If that doesn’t win you over (checks your pulse) then the sly eyed, promiscuous and surprisingly canny Song Joon Ki will with his irresistibly wicked grin. I don’t care how pretty this guy is, he is not to be underestimated.
Put the two of them together, and they are more than just the sum of their parts. Honestly, if I saw the two of them were cast in a puppy food commercial together, I would go out of my way to watch it after this. They are THAT good. And now I've made myself slightly ill with all the effusive praise. Le sigh.

The ONLY thing that was slightly off putting for me was the occasionally startling OST. Sometimes the music was ill advised, sometimes it was distracting. Sometimes it was pretty. It was mostly confused with what it wanted to do.
And critically, the baddies are just bad for the sake of being bad, and I like to know their motivations are something more interesting than entitlement/greed/pure evil. A lot of the gratuitous scenes, while not boring, could have been done away with to give us more on the people we are interested in, such as Cho Sun’s back story, and the terrible two’s 10 year history. The benevolent king- what pivotal moment might have made him different from most? And the eldest Moon brother, his story would have been interesting. Good shows typically leave you wanting more, and this certainly does. I just had fun with it.

Reasons Not to Watch: You don't like K-dramas. Or you need something deeply and intellectually stimulating with no frills.


TL/DR: Just watch it.