Firefox Default for Vista is supposed to replace the blue background in Firefox's default theme with what they deem is a more neutral, gray color. The change is so subtle that we had to switch from the standard theme to the add-on's theme several times to see the differences.
Other than changing the background color, nothing else changed in our browsers appearance. All of the navigational buttons retained the look of the default theme.
Subtle can be good, but this free Firefox theme makes so few changes, it's hardly worth the effort.
Firefox Default for Vista theme basically replaces the irritable sickly blueness away from the default theme when using Vista and replaces it with a much more neutral gray color. This version is the first release on CNET Download.com.