Most high-res texture packs for block games I've seen work by grabbing random slightly related photorealistic textures and slapping them onto blocky voxels, which always give a bit of jank along with ruining the look and feel. This texture pack manages to not do this, by carefully making the new textures be as faithful to the original. They're still high-res and photorealistic, but they do not look or feel out of place. Sometimes, they look totally like the original texture, except upscaled and with a texture to it, as if you can reach in and touch the texture of the grass (heh), or feel the bark of the logs.
In addition, there's also hints of pixelation in e.g. the grass node side texture, leaves or the top log texture. Which just furthers the brilliant atmosphere of a high-res texture pack that is able to work with the fact it is still a voxel game, made out of cubes. It doesn't try to be anything more, and accomplishes very well because of that.