The take away? Star power still matters. The drama -- inspired by a Joseon legend about a mayor who rescued young mermaids from a fisherman and returned them to the sea -- brought together two of the biggest "hallyu" stars to date and went on a ratings rampage since its premiere in mid-November.

Jun Ji-hyun, best known for her portrayals of wild, mysterious and at the same time quirky characters, played the mermaid Shim Chung from the Joseon Dynasty (1392-1910), who travels to modern day Seoul in search of her love.

The mermaid's visuals were in many respects natural and "legit." Using practical and CG effects, the mermaid production, paired with Jun's trademark lanky, slender yet at times powerful and dramatic performance, was met with overall high praise.

The show was Jun's first TV work since "My Love from the Star," which took hallyu fans by storm in 2013-2014.

Her opposite Lee Min-ho played Heo Joon-jae, a genius con artist with a knack for magic and hypnosis. Lee first gained widespread fame from starring in "Boys Over Flowers" in 2009 and continued to ride a huge wave of popularity after his following works "City Hunter" (2011) and "The Heirs" (2013).

Despite the heavy focus on the mermaid, Lee maintained his turf and stood as equals alongside Jun in weight and screen time throughout the show.

Jun and Lee's first collaboration was strong enough to glue viewers to their televisions. The show started with a strong 16.4 percent viewership rating and surpassed the 20 percent mark in the metropolitan area by its sixth episode.

The show, at the same time, wasn't without its detractors. And they had a point.

A lot of the key elements -- such as a parallel timeline and romance between a human and a supernatural being -- were seen as recycled elements from Park's previous work. In the latter part, Hwang Shin-hae, who played one of the villains, managed to keep the show intriguing.

"Legend of the Blue Sea" managed to fare well overseas. The 22 billion-won (US$19 million) show was exported to all major regions around the world, including Southeast Asia, the Americas and Europe, according to its production company Culture Depot.

The show, however, wasn't aired in China due to a political dispute between Seoul and Beijing after South Korea announced its plan to deploy a U.S. anti-missile system on its soil. According to Culture Depot, however, the show was popular in China through piracy. (Yonhap)