Now I don't think this show is ACTUALLY 5 stars however I do believe it is being bombarded unfairly with 1 stars.
People voting it 1 star have a disagreement with comments made about Indonesia in episode 5. I have no ties with Korea or Indonesia so I cannot say I have strong opinions on the matter however if the comments offended people then they should apologize and makes amends.
That said, this series contains a wide variety of different crew members (including young adults) who contributed hard to the series and I don't believe all the hard work should be wasted due to a script writers unnecessary comments.
So, to review the WHOLE show:
Racket Boys is a wholesome show about badminton (to watch you show you don't need to know anything about badminton!), community, friends, teamwork, and classic KDrama drama! An honest rating of the show would be a 3 or 4 star. Like many Kdramas I find there are weak points in the plots (some plots could be fixed if two characters just had a conversation) however that is part of the charm to the whole kdrama category.
On top of that, the show has many humorous aspects that are balanced with more series tones. I think the show is worth watching even if you don't particularly care about sports!