Breathtaking animation, incredible fight scenes. It's not as well developed as the forst Castlevania series, and some characters, particularly the main villain feel criminally underdeveloped.
None of the complexity of Dracula or Carmilla. This is the "I am a God" kind of villain, just because she says so, and her justification for that claim seems, again, underdeveloped. She's God because she's God. Period.
Richter's arc is very good. From cocky, to scared, to badass, he goes through the gamut. Nothing to say but that. I'm thoroughly satisfied witu how they handled him.
Maria and Tera are great characters. You believe the chemistry between the mother and daughter and you can see Maria's power grow through the season, and a huge payoff for their relationship by the end of the season that for me was one of the things I'm most looking forward to in season 2.
Olrox and Myzrak have an unexpected dynamic that I'm intrigued to see the payoff for. Definitely a lot of interesting setup for tense interactions between these characters in an upcoming (hopefully) season 2.
Annette has a tragic and intriguing backstory, but no actual arc, making her the wated potential of the season. She doesn't seem to grow or change in any way. This is just your basic underdeveloped "I'm a badass woman" character that doesn't seem to go anywhere because "the power was in you all along" (you know the type). The interesting part of her arc happened BEFORE the series, she's not as interesting during. I wish they had used her backstory as her arc in this season, similar to how we saw Isaac's journey in the previous Castlevania. The resolution to that backstory would've been triumphant in the finale, but they got impatient, so she gets the most blah part of the finake. Annette is a complete character that doesn't need to learn anything and as such, is not interesting because she has nowhere to go.
Overall I loved Castlevania Nocturne, but I wish they had focused a little less on the "badassery" (yes I know that sounds shocking) and more on building a story and world like the first one did. This was just good, where the previous one was a masterpiece.