The Dock implemented in ML is, IMO, ill-designed and basically makes it unusable. I've filed a bug report for loss of usability, citing these items. First, the previous elliptical app on lights reflected over the edge and were readily discernible. the new, garish, rectangular ones displaying only on the Dock's edge are barely visible. Second, the previously clear icon reflections were replaced by cloudy, unclear blobs of color. Third, app windows dragged behind the Dock no longer reflect any text, just more color blobs if they contain colored images. This is what the previous Dock looked like and indicates what an usable one should display.