Nickelodeon’s upcoming spin-off animated series, The Last Airbender: Legend of Korra, is easily one of the most anticipated TV titles on the horizon. Attendees at the 2011 Comic-Con got an early look at the show, which was conceived by original Avatar: The Last Airbender creators Bryan Konietzk and Michael DiMartino.

The Comic-Con trailer for Legend of Korra has made its way online, and it (naturally) begs the question: How does this new series look to compare to the beloved original Last Airbender show?

In a few words, Legend of Korra aims to be a darker, more mature, and more technically-proficient journey into the Avatar world of element benders and fantastical creatures. That much was made clear back when the show was officially greenlit by Nickelodeon heads just over a year ago.

Here is the official Legend of Korra synopsis, followed by the Comic-Con preview:

“The Legend of Korra” takes place 70 years after the events of “Avatar: The Last Airbender” and follows the adventures of the Avatar after Aang – a passionate, rebellious, and fearless teenaged girl from the Southern Water Tribe named Korra (voice of Janet Varney).

With three of the four elements under her belt (Earth, Water, and Fire), Korra seeks to master the final element, Air. Her quest leads her to the epicenter of the modern “Avatar” world, Republic City – a metropolis that is fueled by steampunk technology. It is a virtual melting pot where benders and non-benders from all nations live and thrive.

However, Korra discovers that Republic City is plagued by crime as well as a growing anti-bending revolution that threatens to rip it apart. Under the tutelage of Aang’s son, Tenzin (JK Simmons), Korra begins her airbending training while dealing with the dangers at large.

Going off the footage show here, Legend of Korra will feature some truly beautiful traditional-animation in order to realize the new Avatar world, including the Republic City – the design for which was based on 1920s era Shanghai and Hong Kong, along with certain elements of early 20th century Western architecture. The element-bending battle sequences look to have been noticeably improved as well, mixing more elaborate fight choreography with an increasingly complex animated filmmaking style, while still retaining the Japanese animation-inspired aesthetic of the original Last Airbender TV series.

Legend of Korra will also feature what sounds like a captivating new protagonist in the form of Korra, who’s both an older and more tenacious character than Aang was in Last Airbender. Likewise, it seems as though the line between good and evil might be a bit fuzzier in Korra’s world, suggesting this new series will indeed be darker and more adult than its predecessor. Of course, it’ll still retain some of the all-audiences-friendly humor and less serious atmosphere from the original Last Airbender show (see: the last scene in the trailer above, for proof of that).

The Last Airbender: Legend of Korra is expected to begin airing on Nickelodeon in early 2012. We’ll keep you posted on its status.