Anyone who want's to use on screen NavBar buttons, he's lucky! (at least compared to ICS).
Now, by adding in
If you want to disable the hardware keys, edit the file
There is a mod** (flash it in recovery) which makes the bar almost half the size. It's better looking and less space is wasted but it does get some time to get used to it and you might need a couple of tries sometimes when trying to hit those buttons.
*This wasn't the case for ICS.
**mod by houssam10001