I've been playing a bit of it and, holy shit, I'm loving everything I'm seeing. It's true, some of the backgrounds and textures still look rough, but I gotta be honest, some rooms you enter actually look really frickin' cool.
And the map, I haven't gone far (been through a few areas, fought a few bosses and stumbled upon a few MORE areas), but if scrolling up to down, right to left is concerned, it's damn HUGE. IGA wasn't lying regarding this being the biggest castle. One area I stumbled across I couldn't go further into because I needed an item or skill, but when I saw it was like, "Holy crap, THIS is in the castle?!" I'm not spoiling it, but it's obviously shown in the Launch Trailer.