It's completely reworked to use Bootstrap toolkit panels.
The contents of the Prefs panels have not been reworked.
More standard user interface.
Lots more room for growth.
The old way was convenient for the programmer, but klunky for the user.
There's one fundamental difference from a user standpoint. When you go to look at another panel the values in the other panels are retained, but are not saved to the server until you hit the Submit button. When you hit Submit, all the prefs in all the panels are sent to the server.
Update both opml.root and worldOutline.root.
Go to the Roots page.
Click on the gear icon for any of the roots in your list.
The new prefs system should show up.
Try changing one of the values and clicking Submit.
It should come back to the first panel of the Prefs, with the changed value visible.