I had pretty good expectations for this one going by the trailers, but to be honest I underestimated how good it'd be. I liked the degree of faithfulness to the original characters, such as Trevor, Sypha or Alucard - while at the same time making them more fun than they ever were. The dialogue was engaging and lively, and it kept me entertained throughout the more chatty parts. The atmosphere, I felt, captured the eeriness and menace of Castlevania perfectly well. And of course the big standout point was the animation, which surpassed my expectations with some fantastic fight choreography and inventiveness in the use of surroundings and weapons at hand. The Trevor vs Alucard fight was perhaps the highlight, but all of it was just a joy to watch, really.
I enjoyed the character of Trevor a lot. His jaded demeanor made sense for the heir of a house which sacrificed their lives to protect mankind for generations and got nothing but scorn and humiliation in return, which makes his turnaround after meeting the Speakers far more interesting than if he had been just this badass relentlessly fighting against evil from minute one.
Sypha was really enjoyable to me, as well. In the fight against Dracula's monsters and also while they were falling through the catacombs, there was this really cool sense of sync and unity between Trevor and her, and she didn't feel overshadowed by Trevor at any point in those scenes. Finally shipping these two seems to make sense, as they both are cool as fuck and have actual personalities now (*wink wink* Castlevania III *nudge nudge*).
The first episode focused around Dracula was also a really good one, featuring both his more humane side and the weight of his wrath against humanity for in their ignorance taking away his one true love. It gives the main villain of this story a very welcome layer and motivation to do what he does, rather than just out of pure malice or arrogance as a superior being.
To sum up, this is an example of a videogame adaptation done right. By taking the key elements that make Castlevania be Castlevania, distilling them into something more polished without alienating the fanbase and adding their own spin to the narrative in a well-executed manner, they've pulled off something that feels familiar and yet fresh, which makes it an entertaining watch for sure. Although in perspective this is merely the opening act for a bigger storyline, it was a damn strong opening act.