After Tokyo is destroyed by a devastating bomb, New Tokyo is born, a city filled with violent gangs, terrorism, poverty, and government corruption. Going beyond a traditional anime, Akira actually made waves by being an all-around great film, introducing the West to long-form anime movies and helping to popularize the cyberpunk movement.
A post-war city is nothing new, but the degree that Akira goes to show how violence has affected the world is what keeps the movie fresh today. Gone are the cheap animation seen in too many cartoon movies and the awkward, hand-drawn pornography used often in anime. Akira concentrates on telling a great story with real social implications.
As a result, Akira became a cult-classic and a great example of how animation can be just as, if not more, effective than live-action when dealing with certain subject matter.