Ubuntu does in fact squash GNOME's beautiful defaults. It also offers up alternate defaults in place of "GNOME Desktop" applications (Firefox and Thunderbird, instead of Epiphany and Evolution, for example). Meanwhile, Boxes (a new application introduced with 3.4) is nowhere to be found; a PPA existed briefly, but has since disappeared. If those trade-offs are OK with you, following the steps below should get you a nice Debian-style GNOME 3.4 environment:
From a terminal, issue this command to install GNOME Tweak Tool and the GNOME default font, "Cantarell":
sudo apt-get install gnome-tweak-tool fonts-cantarell
Open System Settings > Appearance:
- Background: Should be the first option (blue stripes, with clock icon).
- Theme: Adwaita
Launch the program named "Advanced Settings" (this is the GNOME Tweak Tool).
On the left, click "Fonts":
- Text scaling factor: 1.0
- Default font: Cantarell | 11
- Document font: Sans | 11
- Monospace font: Monospace | 11
- Window title font: Cantarell Bold | 11
- Hinting: Medium
- Antialiasing: Grayscale
On the left, click "Theme":
- Window theme: Adwaita
- Cursor theme: Adwaita
- Icon theme: Gnome
- GTK+ theme: Adwaita
(these settings came from an untouched installation on Arch Linux I just did this afternoon)
Ubuntu absolutely squashes the default GNOME sound theme. The drum sounds are completely out of place, I would at least switch to something else (Sonar seemed to be a good trade off). You might be able to extract the original sounds from an archive and overwrite them, or better, create and import a new sound scheme. I haven't looked into this.
GNOME's default browser is packaged as "epiphany-browser", and a useful extension pack is packaged under the name "epiphany-extensions" (including an ad blocker that seemed to work well enough when I tested it). Epiphany is a bit underdeveloped compared to Firefox or Chrome, but if you don't need all the extensions and addons, it's worth checking out simply for the cohesive desktop experience.
I'll leave you to explore the rest of the default GNOME applications: http://www.gnome.org/applications/
I hope this information was helpful!