Something else you may not know (or care about) is that I try to re-watch the films I recommend in effort to have something fresh and unique to say about them. When I re-watched Batman Beyond: The Return of the Joker, I found nothing new to think or feel about it, other than it remains a solid entertainment fifteen years after its release. And, it stands strong among the multitude of DC Comics animated movies, most of which have been consistent in their high quality.
Like the best adaptations of super-hero comics, RotJ grounds itself in its source material and uses that to spring forward with a compelling story of its own. That in and of itself is what we comic book nerds really want in the film adaptations featuring our beloved characters: connection to the old while bursting towards something new. And, for some reason, Batman and his mythology seems especially capable of maintaining a solid core while allowing for some exciting change.
Batman Beyond is a prime example of this. It started out as a follow-up series to Batman: the Animated Series, set approximately fifty years in the future of the DC Animated Universe as created by Bruce Timm. A new, younger Batman is now protecting Gotham while an elderly Bruce Wayne acts as mentor and guide. The new Batman is Terry McGuinness, and he is less grim, more humorous than his predecessor. He also has a suit equipped with all the latest technological advances one would expect to find on a Batman suit fifty years in the future. It was a fun series that carried on the tradition and standard of quality begun in Batman: TAS.
As a feature length film, RotJ does the nifty trick of fitting in smoothly within the continuity of the series, which was still airing when the movie came out, while presenting a complete, self-contained story so non-fans or casual fans (like me) could appreciate it. The story is indeed about the return of Batman's ultimate arch-nemesis, and that mystery fuels the action, particularly since it had already been established in the series that the Joker was long since dead.
The answer behind the Joker's return is a great reveal and satisfying in how it ties together the past and present of the Batman Beyond continuity. Plus, fans once again get to hear Mark Hamill's legendary portrayal of the Joker alongside Kevin Conroy's wonderful voice characterization of Batman/Bruce Wayne.
But, that is just the icing on the cake of a very well-made animated film that pleases fans of the TV show while being solid entertainment for those who just want to see a good Batman movie. Fans and non-fans alike will enjoy what Batman Beyond: The Return of the Joker has to offer.
(Side note: RotJ has also become just as famous for the many edits it had to undergo in order to get a pass to air on television. The blu-ray disc has both versions, and I think either is acceptable as complete, fully-realized movies, but neither version is suitable for children under the age of ten in my opinion. The unedited version is rated PG-13.)