It now has a uniform menu tray that pops out from the left side that looks the same across all screen sizes, which allows users to navigate to any part of Facebook without needing to go back to the home page -- meaning it's easier than ever to get sucked down a rabbit hole of baby pictures, witty comments, likes and pokes.
They utilize the increasingly-common side menu that can be accessed via a swipe to the right (or button press in the top left corner) and visually seems to appear from under the main inbox screen.
Quick settings can also be accessed by pulling it down from the top right portion of the screen, whereas the notifications menu is hidden in the top left.