Glancing at these screenshots, it looks like Facebook 6.5 has less vertical space for displaying content as a result of this change. It looks like the menu at the top got split into two: a portion at the top and an expanded portion at the bottom. I cannot say I am particularly impressed, if correct. I prefer a minimalistic approach to UI design -- much like post-Chrome for web browsers.
9/18/13 at 3:14pm