I love this movie. It is way beyond any of the live action movies of the time. You get some background on Batman. While everyone knows the ‘parents shot in alley, dress like bat’ origin, this was the first real look into his pre being ‘THE Batman’ days. The movie also has a love interest that is actually interesting. Oh, and a Joker that is actually creepy, funny, scary and not a waste of time like Jack. (Hate his Joker so much).
The voice cast have become iconic for so many people. Kevin Conroy is my Batman. Mark Hamil is my Joker. Efrem Zimbalist Jr. is my (& the best) Alfred. These are the voices I hear when I read a Batman comic.
What I feel help sets B:TAS apart from pretty much every other cartoon of the era (and beyond) is the art style. By going with backgrounds painted on black paper, the series has such a unique look that still looks amazing. And by going with a retro-noir feel, everything is eternally timeless. It never feels dated, because in a way, it always has been. Going back to say the 90s Spider-Man, it has not aged well.
Bruce Timm & Paul Dini (et al) were able to take Batman and treat it seriously. Yeah, there is inherent silliness in a guy dressing up as a bat, but they never treated it like a kids show. I enjoyed it as a kid, but I think I appreciate it more now as an adult.