Speechless. I was left speechless by how tight the gameplay is. I don't know how to put it into words other than "it feels like money". For every cut corner made to the visuals, presentation and so forth, you can feel it all reinvested hand over fist into the gameplay. Those of you familiar with backdash crouch canceling from previous Iga-vania's will be pleased to learn that the movement tech is back, and yes, it's superior to simply moving forward. I played throughout the entire game on KB+M, slain every secret boss, and had very few gripes with the setup. The most I could complain about the controls would be that right-click targeting feels a bit wonky, and using the Invert spell command (W+S+Space) felt inconsistent. I may have been inputting it wrong, mind you. And just to be thorough, I will also say that I had some trouble inputting the directional commands (quarter circles and such) using WASD. If it makes you feel any better, rhythmically tapping S and Q to backdash crouch cancel feels better on keyboard than controller.
All of this aside, it feels like a genuine successor to Iga's Castelvania titles, and a worthy one at that. Mechanically, it's a greatest hits collection of Symphony of the Night, and Aria of Sorrow. Tight level design (aside from Den of Beasts and a few other end-game dungeons), a myriad of unique spells, extremely fun and challenging bosses, eureka moments for progression that reward you for paying attention to details, awesome weapons that can further differentiate themselves within their own sub-category, and meaningful character upgrades made the past 23 hours I dumped into this game feel like mere minutes. It's worth mentioning that there're some bugs here or there, but nothing critical that screwed my game up. Either way, I'm glad this game is a critical success, it deserves it.
Hope Iga has plans for a sequel; he's made a believer out of me.