Korean Drama "18 Again" handled the fantasy element perfectly, except for the ending.

The drama had a nice start and it added a lot of new elements to the story, with the struggles of the twins, the progress of the main couple's relationship, and the female lead's professional career. However, the drama opted to focus on the romance towards the ending, a love story that was okay at first, got tiring though. The main lead kept popping up and staring at his love interest way too many times and the jealousy card was overplayed as well. The ending, in addition, was too sudden and didn't fit smoothly with the rest of the story. Still, the character development was spot on and the side characters were funny.

As for the performances, everyone in the cast did a great job with their roles.

So, overall, 5 out of 10.