I've been using this for several months now, and it's been absolutely wonderful.

I'm a student, and because of online classes, I spend hours each day staring at my screen. With this extension, I'm able to hide distracting/pointless webpage elements and make websites easier on the eyes. For example, Google Docs currently has no built-in dark mode, but it's very easy to write your own dark theme using Stylus. This extension has saved me a ton of headaches and made browsing the web more pleasant in general.

The only thing some users may struggle with is the fact that there's a bit of a learning curve to using this. There are lots of pre-made themes out there for various different websites, but writing your own styles—which is preferable since you can't depend on other style authors to update their styles regularly—requires some CSS knowledge. I didn't have much CSS experience when I began using this, so the first few weeks were challenging. However, I'm still giving this five stars because that issue isn't something the devs can fix, and using this extension has significantly improved my familiarity with CSS.