The new user interface for directions is aimed at making it easier to understand requesting those directions and then following them. They me take you through some of the user interface changes.
Besides for the new icons, you also now get the start time of your public transportation trip, so Google can better plot the options:
Then the suggestions directions are much cleaner and more colorful, to better illustrate the various options:
The directions, once selected, then make following them much easier. The new graphics and icons are easier to read and understand. Google has even added a vertical dotted line to symbolize any walking required during a public transit directions.
Finally, Google also added more detail to the directions. They show preceding stops and also added turn by turn directions for walking, driving and biking.
Finally, Google released the Navigation App for Android for those in Australia. More details on that can be found over here.