Please see the attached screenshots. Adwaita looks lovely in Gnome Fallback (aka Gnome Classic or gnome-panel) but Ambiance & Radiance do not blend right. It's probably worth looking at Adwaita's code to see what they do exactly to support Gnome Shell & Fallback. Perhaps light-themes uses too many hacks that don't all work well with the Gnome 3 switch.
This is a high priority as a decent amount of upgraders who will try to keep using Gnome Fallback even though little developer time is spent to keep it working. And since there is not an obvious way to change the theme in Gnome 3, they may not know that switching to Adwaita will improve the appearance, or know how to do that either.
DistroRelease: Ubuntu 11.10
Package: light-themes 0.1.8.21
ProcVersionSignature: Ubuntu 3.0.0-8.11-generic 3.0.1
Uname: Linux 3.0.0-8-generic x86_64
Date: Wed Aug 17 18:21:31 2011
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007)
UpgradeStatus: Upgraded to oneiric on 2011-06-17 (61 days ago)