OK so ive read some of the replies to this thread and here is my take. For me it was my first kdrama and I watched it for Taehyung.  Here is what to expect.

1) if ur like me, this is the first drama with 2nd lead syndrome (certainly not the last)

2) the romance of the main 2 wasn't that great and it was even a little weird.

So, in the show basically, the lead, ah ro, has  brother who ran off or something. Then he had a bsf, before they make it back home, the brother dies and his friend, moo myung, takes his place. (they havent seen eachother in years. He pretends to be her literal brother so he can join the queens special pretty army. He basically ends up wit hte girl he was pretending was his sister. and his bsf's sister no less. Its kinda weird.

3) There is a lot of heartbreak, when hansung dies and when moomyungs friend dies. Also when jidwi doesnt end up with ah ro. 

overall, good beggining drama, 10/10 would reccomend, because theirs no irritating 2nd female lead and overall good story. and lowkey you fall for all the guys