It's a UI modification. There's very few perks and alot of negatives about it.
The biggest one to stand out in my mind is if you are playing a game, or video, or anything else, and someone messages you from Facebook - it will cut off the left side of your screen until you dismiss it or reply.
But yes, it can be removed. It should be available as an app for most devices running Android 4.x and up, and would require root access to modify the UI.