ATI CTO for graphics Eric Demers told FUD Zilla that the upcoming RV870 will be a huge leap forward compared to the R600 and RV770 GPUs:
ATI’s CTO (Chief Technology Officer) for graphics, Eric Demers has confirmed that the chip that they call Evergreen, DX11 is the biggest conceptual chance since the time ATI has introduced rather unsuccessful R600. R600 is the last core change in ATI's GPU design.
The RV770 can be seen as R600 done right, with lower power consumption, smaller transistors and a brand new GDDR5 memory controller, but it was not built from the ground up. At the same time, RV870 should be a huge leap forward in ATI’s chip design compared to R600, RV770, Eric confirms.