This style does two main things:

1) It shortens the 'highlights' area found on the home page after the most recent update, and adds a scroll bar. This makes it a bit easier to see the items found beneath the highlights area (like pokes, friends you may know, etc.)

2) It removes the image/video preview pictures found with each highlight story. Again, I didn't find the previews to add anything useful to it, and this is a little more space efficient.