These scrollbars are awful. Yes they may look pretty but at the expense of usability — just like everything else in Unity.

— You can no longer click anywhere besides the gripper to quickly scroll to a given position.
— The gripper doesn't appear anywhere besides next to the highlighted area in the scrollbar so you can't quickly jump to places
— The gripper doesn't appear as quickly as I'd like. I have to mess around with my mouse over the top of the highlighted area a bit sometimes for it to show. This is frustrating!

But OH MY GOD we get 5px of extra screen real estate! SCREW USABILITY!

EDIT: For anyone wanting relieve themselves of this horrible 'feature':
sudo apt-get remove overlay-scrollbar
sudo su
echo "export LIBOVERLAY_SCROLLBAR=0" > /etc/X11/Xsession.d/80overlayscrollbars
reboot