This is one of the selling points for me as well. Literally just before opening HN I've looked at my overflowing bookmarks toolbar and thought "Those folder icons and default favicons feels quite unnecessary any only occupies precious space. Let's get rid of them." and then did exactly that in few lines in the userChrome CSS [1] and voilà, toolbar no longer overflows.
I don't think any other major browser lets you do that.
This is one of the selling points for me as well. Literally just before opening HN I've looked at my overflowing bookmarks toolbar and thought "Those folder icons and default favicons feels quite unnecessary any only occupies precious space. Let's get rid of them." and then did exactly that in few lines in the userChrome CSS [1] and voilà, toolbar no longer overflows.
I don't think any other major browser lets you do that.
[1]: https://gist.github.com/myfonj/f5415dd0580663a82ea18407ef2ee...