I'd say it's a solid 8/10
Story is enjoyable, but the season is too short to be really compelling
Every episode as at least one really awesome action sequence. Whip fighting is way fuckin cool.
The art direction is really striking and the character designs are visually distinct without seeming out of place
They've made some changes from Castlevania lore. If you're a lore purist you might not like them.
Crude humor. That's the sort of comic relief they're going for, so if you don't like that sort of thing don't expect to laugh much.
Low fps. Better art quality and low animation quality typically go hand in hand. It's not as fluid as simpler drawn cartoons. I think it's worth it for the level of fight choreography, but some can't look past it.