Not only does it look nicer - it's stable, a more recent build than that in Ubuntu and... well.. it looks nicer! Look!
By merging the toolbars, buttons and breadcrumbs, Elementary Nautilus makes the best use of space. And yes! You can still have your sidebar, too!


Installation
Open a terminal and type the following commands, hitting your return/enter key after each.


sudo add-apt-repository ppa:am-monkeyd/nautilus-elementary-ppa
sudo apt-get update
sudo apt-get upgrade


Then either log out and back in to use the new Nautilus or manually do it by pressing Alt+F2 and typing: -
pkill nautilus
Now we need to launch nautilus, so press Alt+F2 again, this time entering: -
nautilus
To hide/show the "menu bar" as in the screenshot hit Alt+M.
To toggle the sidebar use 'F9'.


Uninstall instructions
If you try it and decide you miss excessive chrome you can install the "old" nautilus in a few clicks.
Remove the above PPA from your sources list (System > Admin > Software Sources > Other Software): -
Then run the following commands: -


sudo apt-get update
sudo aptitude install nautilus