I could tell you about the list of improvements as long as my arm, including vastly increased memory bandwidth, 65nm fabrication, and huge increases in shader and thread counts. I could bore you with more technical specs and statistics.
But I think what you really need to know is that it runs Bioshock at 2560×1600 with 4x anti-aliasing and 8x anisotropic filtering at nearly 60fps. If you’re rich enough to have a monitor that supports that resolution (or a couple), you may just be interested in shelling out the $650 for this titan of a card. Look at it. It looks like science fiction.
And yes, it runs Daikatana.