Following are some of the important improvements:
In addition to the visual tweaks you have seen already, such as the Speed Dial facelift, we have also been making further UI enhancements. You will notice that the O menu button now says “Menu” for easy discovery, and instead of hard to read thumbnails for internal tabs, we have replaced them with icons. The tab hover previews have also received a facelift.
More information and versions for other platform can be found here.