i think the card was direct replacement for GTX480. it perform as good as 480 but consume power much more like GTX470. another plus side is the card is less noisy and run cooler with nvidia new reference cooler.
It has the core of the GTX480 with the memory specs of the GTX470. Seeing as the GTS470 has enough bandwidth, it performs like a GTS480 most of the time. Basically, if you wanted a GTX480, the GTX570 will do. If you already have a GTX480, its not an upgrade.