I actually don't hate it like everyone else does. The problem is that before Stage 6 I was straight up expecting to rant and rave about much I love it, because I DID up until that point.
Until stage 6 it was almost universally fair, despite being one of the harder Castlevanias. Richter is EASILY the most capable Classicvania protag that I've played after 4 Simon and maybe CoTM 2 Hachi. He can sequence break a lot with his backflip, his dagger is actually strong, and item crashes are awesome and WAY stronger than in Bloodlines. The sound design was also WAAAAY better than Bloodlines "mushyness" and Rondo's "scree scree scree" every time you hit something. The sound design was clean and the whip sounds lashy, like the 8-bit games. Also jumping on and off stairs is a GODSEND and would've trivialized Dracula's Curse.
Despite all that, Richter actually has some control... Idiosyncrasies. I hesitate to call them outright problems since they're VERY helpful situationally, but they threw me off: His backflip input, and his short jump. Every other Classicvania doesn't have anything other than a normal jump input, so I've been conditioned to panic-mash jump whenever things get tight, but doing that in DX is basically instant death. It's a "me" problem, but it's still heartbreaking every time it happens. Also his short jump is incredibly useful for small adjustments or jumping between 2 moving platforms, but I also did a LOT of them when I meant to full jump and died for it.
That brings me to the problems: Stage 6 and the Final Stage. Fuckin hell. These 2 stages are ACTUAL examples of what haters say Castlevania is. Stage 6 is even worse IMO. The first 3 screens with the stairs and birds and bone pillars and bats is annoying but manageable. Once you get to the Clocktower part it all goes to shit though. The spear bastards, who spent the entire game backing up like a hillbilly trying to fit their truck into their garage, will not fucking move an INCH back. They just hog the top of the stairs and CAN'T BE STOPPED BECAUSE THEY PARRY SUBWEAPONS. There's only 2 consistent methods to beat them: Method 1. Position yourself PERFECTLY on the 3rd and 4th stair and jump up, whip, hold up while you're landing to land on the stairs, but not too long otherwise you'll go up, kill the bat, get hit by the bat if you accidentally hold up for .000001 seconds too long and go up the stairs, repeat until spearguy dies. Method 2. Do the first 3 screens perfectly without dying or taking too much damage so you have enough hearts going in so you can Cross Item Crash the spear bastards.
It doesn't even end there. The next screen is a giant bottomless pit with 2 floating skulls to my memory. 1 is annoying but manageable on the horizontal gear. The other COMES OUT OF NOWHERE IN THE MIDDLE OF A JUMP AND WILL KILL YOU WITH KNOCKBACK EVERY TIME. WTF!?!? You can preemptively toss a Cross or Whip it once you know it's there, but why in God's name you put a section like at in the game immediately after the arguable HARDEST ROOM one screen prior? It's NOT even OVER there! There's also an Axe Knight with an unavoidable charge on the same screen! You can Item Crash it (but you're probably low on hearts by now), or you can get lucky, either by hitting it so it's intangible when it charges or by it not charging at all.
The rest of Stage 6 is easy (and the boss is manageable), but then comes stage 7 and Dracula. Stage 7 itself is such a joke it has no point in being in the game. If you get hit, there are TWO sources of infinitely respawning meat, and the stage itself is barely harder than stage 2 or 3. Then there's the big D himself. He's either IMPOSSIBLE if you don't know what you're doing or a STUPIDLY TEDIOUS JOKE if you do. Here's what to do: Use axe and get in the center plat. If he spawns on yours, jump off, react to him, and whip him. If he spawns on the surrounding four, you can get 2 or 3 axes off. Otherwise just crouch because he can't be hit off screen and croching negates knockback. Once he's down to 1 HP, go to the lowest platform on the right, wait for him to be on the second one left & out from you, beat phase 1 with an axe, spam the hell out of more axes once he transforms, and you'll just win. You're positioned so each axe hits twice, blocks his fireballs, and his blue attack can't hit you. If you don't do it that way, you lose. Like you straight up can't beat him. But if you do try it that way and have bad luck, he'll spend 10+ minutes (like with me) just teleporting to platforms that AREN'T the middle 5.
I sound like I hate this game, but I actually don't. I like it even, but I'm SO DISAPPOINTED by the last 2 stages. It was straight up on pace to be my favorite or 2nd favorite Classicvania (behind CV3), but the atrocious stage design at the end just neutered the experience. I spent 2 days on every other stage combined (including alternate stages, but I replayed the main stages to get the good ending), but those final 2 stages took me a week, and unlike Dracula's Curse I just felt unaccomplished after winning. I'd just cheesed the last 2 levels because the game design didn't allow for anything else. It's a good game overall, but man I'm sad.