Although I get used to the on screen key (my previous phone is Nexus), I still set my OnePlus One to use capacitive keys to get more screen space. Another reason is that you can add more functions to the capacitive keys for long press or double-taps.
Under the Buttons setting, I set Long press action for Home button to invoke Search assistant (Google Now). Double tap Home button will display the Recent apps switcher (similar to the right on screen key). Long press on Menu button will switch back to last app.
Even on the lock screen, you can give more functions to the capacitive keys. Under Settings, Button actions, you can add more actions to capacitive keys. For example, you can choose Home unlock. This means after you double-tap to turn on the screen, you can just press on the Home button to unlock, no need to slide.
Battery Status Reset
Battery status on OnePlus One has a additional feature which allows you to reset the battery status.
Just click on the Garbage icon on the top right corner. The battery status will reset. This is useful when you want to check if any action you take has immediate impact on the battery power consumption.
USB OTG Support
OnePlus One supports USB OTG out-of-the-box. No need to install any software or root, just plugin a USB OTG cable and a USB drive, or directly plugin a OTG USB drive.
Once plugin, the Storage settings will be displayed and shows the options of Unmount and Erase. Now you can use File Manager to browse the content in the USB drive. You can directly view the photos or play movie in the drive.