I finally got around to watching this drama! I've had it on my list forever just because I like the main actors, but I wasn't sure whether or not I would like the show based on the description. I took the plunge last week and was so glad I did. This show hooked me from the first episode. D.O's performance of Joon Young was chilling. I thought that the child actors did a great job as well - (those brothers are adorable) and the boy playing a young Hyun was well cast especially. The acting was great from all the cast, though, and Park Bo Gum's facial expressions were on-point. I thought the storyline was well-done, and it kept me wanting to know more. I liked the suspense of it and how the story unfolded a bit at a time, but it's not as suited to a re-watch because the suspense is no longer there. I also enjoyed the bit of comedic moments as well, and the hint of romance. The bromance between the brothers was really emotional, and somehow the writers even made the "bad guys" sympathetic characters. There were very few missteps, and I thought it was a solid choice.