I personally don't have an issue with 2.5D. Look at Lords of Shadow Mirror of Fate HD, an upscaled 3DS game. Coming from seeing what Mercury Steam could do with 2.5D on the 3DS, it's very disappointing seeing what's been done so far with Bloodstained.
Compared to the below, I really hope they're just testing out different techniques on what they'll use to finalize the graphics and it looks much better, but like I said, I doubt it. Despite that, if an amazing gameplay comes out of it when it comes to gameplay, then the graphics will be a disappointment, but obviously something I'll live with.