GQ 1.2.0 is the first stable release of a code base that has been developed the past five months. It contains several improvements to GQ 1.0.x even if not every glitch is fixed yet. It's the start of the next 6 month development cycle which will go on and start introducing significant improvements.
Building GQ is a lot easier now. We don't ship our internal copy of libintl anymore, so lots of build problems related to libintl just disappeared. Other changes to the build system raised several dependencies (you can't build with GTK+ < 2.6.0) or introduced new ones (gnome-keyring for those Linux users out there), but the overall experience is a lot better right now.
Another issue that has been improved was the proper handling of LDAP_DEPRECATED for OpenLDAP 2.2 and newer.

We finally fixed the setup for the desktop's application menu.
The main window doesn't look very different from previous releases (you might realize that the Help menu item moved away from the right directly after Filters item).
There have been some changes to the connection mechanism that allow anonymous SASL binds. Something that really increases the level of security has been the introduction of Gnome Keyring. Using GQ 1.2 will migrate the passwords from your configuration file into the keyring where they will be encrypted.
While working on your directory, people without libcrypto and libssl support (such as Debian and Ubuntu users) can get password encryption through libgcrypto. This is the start of providing replacements for the OpenSSL stack. It's far from being complete, but it's implemented to see that it can work.
Summarized as "lots of things changed, but almost nothing is visible", the 1.2 release went the way of stabilizing the code base and removing passages that have been hard to maintain.
There have been lots of changes to the internals of GQ. This makes the code both a bit more robust and also more consistent with the APIs from the Gnome development platform. These changes have been implemented mostly to pave the way of GQ in the future.
GQ is far from being perfect, so we're continuing the development in two branches: