TNBA was a great show. Sure, a few designs were off, but it both retained the level of quality that BTAS set, and further adapted the Batman comics of it's generation. Introducing Tim Drake as Robin (a combination of Drake and Jason Todd, who they thankfully skipped), and moving Dick Grayson into the Nightwing persona helped make it closer to the comics, among other elements, while giving BTAS a firm history.
Also, I can't recommend 'Over The Edge' highly enough. It stands as one of the greatest pieces of Batman animation ever, perhaps even one of the greatest Batman stories ever.