Not much different with the stock Roboto font. But it's bolder + thinner and look better.
UPDATED (20130721) :
Updated the zip package with Roboto Condensed pulled from leaked Android 4.3.
Subtle changes that you barely can see. Click for more details: Facelift in Roboto in JB 4.3
To install, simply download and flash it in CWM or TWRP recovery.
Download and flash this:
Revert to stock:
Enjoy the fonts!
*credit goes to Google Android team for these beautiful fonts
Flash it at your own risk!