I want to base this on what the anime IS rather than what it could have been. That said, I really enjoyed BNA. The characters were compelling, the universe was intriguing, the art was stunning, and while the anime didn't accomplish anything particularly revolutionary, I thoroughly enjoyed every episode. It was a good concept with some parts that could have been elaborated on or explored more, but in 12 episodes, I still got a good sense of the world at large, the challenges characters faced, and the overarching themes. For a 12-episode anime, the plot was really well-done with a good amount of build and a satisfying (although some might say lackluster) resolution. Character design was 10/10 with diverse body types and a stunning lack of hyper-sexualization. Music was very good. Art and animation, incredible, especially during the scenes with more action. Some heavy topics such as prejudice, discrimination, and eugenics, but they didn't feel glossed over or heavy-handed which was refreshing.
This review is pretty scattered, but in short, certainly not the best anime in the world but definitely worth watching.