Since the release of Quantum, and whether standard or via Speed dials, this is so far the best way to display bookmarks. Speed dials in Quantum are a joke, and the bookmarking features native to FF have not changed in forever. This extension can produce beautiful and useful results.

It is not without bugs however. For example, using the "modify this bookmark property" submenu can result in unintended and often serious issues. So far, I have had it change every bookmark in a folder to match the changes of the SINGLE bookmark I was working on. Removing a bookmark can result in the removed bookmark being duplicated several times within the folder. Bookmarks rarely, but occasionally, just disappear after being edited within the webextension, and so on. The issues with using the Bookmarks Home menu and submenus is bad enough that I no longer use it, and use the built in FF editor. On the other hand, once you figure out the foibles, the results are brilliant.

Backup your bookmarks regularly using the FF built in backup, and manually copy your custom CSS scripts from the editor and save them somewhere.

Finally, there is no way to now use the extension as a New Tab page.