The OnePlus One smartphone runs on CyanogenMod, which gives it a very fresh new look and feel. The smartphone gets some features, which are otherwise unavailable on other Android smartphones or available only after you root your phone. So here are the pick of the lot.
Heads Up Notifications
It's not a big deal, but heads up notifications really help when you're playing games or watching videos etc. They don't interrupt with what you are doing and you can easily swipe them aside to get to them later.
On Screen Buttons of Capacitive Keys
You can go into Settings -> Buttons to turn on or off the on screen buttons. If you're coming from a stock Android smartphone, then this would be your choice. In addition, the Capacitive keys on the phone are turned off when you use on-screen buttons.
Camera App
While the camera app has some quite useful features, the ability to swipe to change modes is a good addition. You can simply swipe from top to bottom and the mode changes.
Note: The dot on the screen shows on-screen touch.
Screencast app
The screencast application is a very nice touch. It lets you record the activity on your phone, which can then be shared with anyone or stored on the cloud. You can also turn on the 'Show Touch' option if you need to.
Themes
Themes are a big part of CyanogenMod's portfolio. You can go into the theme store and choose free or paid themes. What's good is that you can mix and match and have icons from one theme and wallpapers from another.