It was great seeing all the less popular heroes from DC comics getting a piece of the action, the Question, the Huntress, Hawk and Dove. The character development was good as well, nice stories, great animation, good show for a comic book fan like me.
Bruce Timm, Paul Dini, and the rest of the crew just keep getting better with every series they do. Almost every DC superhero you can think of makes an appearence, so this is a comic book geek's dream show. Every episode has a great plot and top notch animation. I really can't say enough good things about JLU.
If you liked any of the DCAU, you will love this series. Since there are so many more heroes, you get less time with each one, but the core 7 still have plenty of screen time. The stories are not little 1 hour independent episodes but long story archs, especially onc e the cadmus story starts. Great story, character design and development, and amzing visual and voice acting. Bottom line, this is a must own/rent. This is, IMO, the best animated series I have ever seen as a whole, and my personal favorite right in front of The Simpsons(not the last 10 years but the first 8 or 9).