Maybe I'm wrong, but I've an impression that redesign uses much more screen space. Which is not very good for usability in my opinion, at least for existing users.
The old design [1] only used less space because its buttons were way too small and impossible to understand - Bad on desktop, unusable on mobile.
The new design uses more space to clearly label every button and differentiate between actions and information. _And_ it looks better doing it.
[1]: https://upload.wikimedia.org/wikipedia/commons/1/14/UBlock_O...
- no 'new tab' option in the menu - URL/search bar is finally at the bottom, but when you use it it moves to the top. very annoying little detail.