Penthouse is really similar to Sky Castle. The twins, rich families, competing, murders, liars, betrayals, and friendships. Anyway, in the beginning, the storyline was a lot smoother than the end. In the end, there were tons of storylines, so it can be a bit confusing and much for some. I notice that the same music plays over and over which was a little irritating and kind of made me hate the song. However, I did feel that it added to the "classical mood" of the story. Also, if you're a sensitive person, I would say not to watch this drama. This drama deals with things like suicide, murder, and stuff like that. If you liked this drama, I would recommend you to watch Sky Castle. Overall, it was enjoyable, but I wouldn't watch it again.