How so?
Genuinely curious. Not complaining about the performance.
For one, there's simply a whole lot more to render.
The 3D environments are huge, littered with high quality assets, with fairly impressive polygonal subdivision; distant objects and structures that are curved or spherical have nearly perfectly round edges. These assets also boast detailed, high resolution textures. The materials of these assets appear to follow the basic fundamentals of BRDF lighting, with specular highlight distribution varying with each material based on well established physically based models.
The shadow quality is impressive. Lots of blurred samples for real-time soft shadows, with variable color, falloff and density, depending on the lighting conditions and the distance between the shadow caster and the surface onto which the shadows are being cast.
Ambient Occlusion appears to be implemented with an approach similar to Directional Occlusion, resulting in very accurate occlusion of ambient light, as well as indirect shadows.
Grass rendering is a mix between polygonal blades and texture masks rendered in swathes across the grassy fields, giving the grass a fuller, more lively appearance. Specular lighting is also used to great effect on the grass textures (and foliage in general).
Waters shaders use proper refraction vectors to refract surroundings. The surface of the water is animated with lots of tessellated vertices, properly glinted with specular highlights. From what I can tell, however, there does not appear to be any interactive vertex displacement. There are also caustics, but they may just be an effect applied separately to the environment. I'll have to check on that later.
Camera has an actual focal length for DOF, with iterative blurred samples based on focal range and focal loss. No cheap guassian-esque blur like the previous Kirby games.
There appears to be real-time reflections and global illumination as well, but I'll need the actual game in my hands before I can determine the implementation of these features.
I actually intend to do a full analysis of the game after it releases, and wasn't really going to say anything about it until then, but there are simply too many misconceptions keep that under wraps.
