The only thing I've noticed is that some video files play smoother. I know the capabilities of the GPU haven't changed, but maybe putting everything on 1 die sped up mem/gpu/cpu bus speeds or something.
DVD is much quieter too. I own a Xbox Pro (Falcon) Arcade (Jasper) and now the Xbox S (Valhalla). I made a previous post at the bottom of this thread:
http://thegreenbutton.com/forums/p/90344/463227.aspx#463227
HTPC: Intel E6750, 4 GB DDR2, nVidia 8600 GT OC, 2.8 TB Storage, 2 Hauppage 2250s, LG GGC-H20L, nMEDIAPC Black 288BA, Win7 Ultimate 32-bit, 3.7 TB WHS, 2 Xbox 360s, Xbox 360 S, DMA2200 (for sale), 3 1080p displays and an old-school CRT.