I know there's lots of polish and improvements to some of the major rough edges in GNOME 3.2, but I think that of all changes in this release, Epiphany really stands out, as you can see in blog posts by Xan and Diego.
Work to bring GNOME 3.4 to Debian wheezy users has been underway for a few weeks already, and some bits and pieces have been hitting unstable since the tarballs were released a pair of days ago. We still need more base work to be done before some exciting components like GNOME Shell can hit our archive, and we want to fix as many FTBFS with GLib 2.32 bugs as possible before pushing it to unstable, but all in all, hopefully this time, shepherding a major GNOME release to Debian testing won't be as painful as it was not so long ago. However, we have already identified some fun bits involving clutter, cogl and mutter in our initial analysis, but nothing that hopefully can't be dealt with in a civilised way.
As always, if you think you can help us, we're reachable at #debian-gnome at OFTC!