Top-level categories of commands do remain, though not in the traditional "File | Edit | View..." organization made almost canonical by Apple. In their place are command categories along an upper bar of tabs that now more closely resembles the conventional menu bar. But the contents of the ribbon, for each tab you click on, never descend on top of, or cover up, your work.
Icons that are used more often are now bigger, and have items clustered around them. For example, the Paste icon is featured in screenshots as much more prominent, in the upper left corner, in the Clipboard palette of the Write tab.