Overall nice for programmers who are used to dark theme, subject to the technical difficulty to force a dark theme on complicated sites.
For end users, some CSS knowledge does help when the default style overrides do not work perfectly.

May a little feature request? A toolbar button to toggle between different dark styles would be very great, since some sites work better with `filter: invert(100%)`-based styles, some work better with `background: black; color: white`-based styles. Currently I have to go to the option page frequently to switch between the two families.