The noise levels of the Nikon D3 are extraordinary by digital SLR standards. But higher ISOs such as ISO 25,600 can be usable but less than pleasing. See for yourself in Nikon D3: Noise (part 1).
I’ve collected the Nikon D3 information this site into a Nikon D3 Table of Contents page. Future D3 comments/articles will be found referenced from there.