Honestly, don't listen to any of the garbage that people who give it 1 star reviews are saying. I am a HUGE fan of netflix animation (Blue Samurai, DOTA, etc.) and anime in general. Favorite anime being FMA: Brotherhood, Parasyte, etc. (I think that's all I need say to showcase my credentials).
While this doesn't measure up to the novelty, pace, and plotline of the original Castlevania, the story is still engaging, the writing is FINE (I do not understand the reviews trashing the writing), the animation is gorgeous, and the progression is well done. After the first 10-15 minutes of the show, I was thoroughly engaged and I thought they did justice to the first season of what I believe will turn out to be a great squeries.
Music is also FANTASTIC and they introduce enough new magical elements/characters to keep our nostalgia well-fed but keep things interesting.
I honestly feel that people might have been paid to give those 1 star reviews, it's really very odd. It's also disappointing, because the Google Reviews kept me away from this show for about 4 months longer than I would've liked.