Much of the runtime is dedicated to Leafa explaining the Grand Quest —reaching the top of the World Tree to be reborn as an "Alf" and gain unlimited flight.
The conclusion of the three-episode Excalibur mini-arc is widely considered a "fun, refreshing break" from the series' darker themes. Sword Art Online Ep. 17: Captive Queen - oprainfall Watch Sword Art Online 17
Depending on which season of Sword Art Online you are currently watching, Episode 17 varies significantly in tone—ranging from a world-building "setup" episode to a high-octane battle featuring massive character returns. Season 1: "Captive Queen" (Episode 17) Much of the runtime is dedicated to Leafa