Though both companies are coy about bandwidth and compression, in brief trials both systems generally sounded good, even smack in the middle of a big aboveground parking structure.
By comparison, in dealing with the vast realms of low-content data, just about the only way to cost-effectively refine down to the good stuff will be through high-powered data compression.
If you couldn't tell from the pictures already, they both look very good, and although the HD DVD version has more detail and no compression artifacts at all, the Apple TV has less compression then expected.