Hard for the genre? Or hard for a Castlevania game in general? Because the recent Castlevania game that I've played weren't very challenging, although people have said that they've been getting better about this.
If you mean hard, even in comparison to the old ones, then I should probably stay away. I can played Metal Gear with my eyes closed, but the old Castlevanias used to whip me.
Hard compared to most of the more modern series.
The thing is the damage enemies do is fucking insane. It's far higher, and dodging enemy attacks is harder than in other modern CV games.
FWIW, the modern CV games have up and down difficulty. Like, COTM is probably the hardest of the modern style ones, while I'd say this one is likely the most unfair. It shares some of the issues that HoD did, in that it's hard to dodge enemy attacks, but for different reason(In HOD, your whip is not long enough. Enemies typically have way longer range than you or are faster).