Absolutely phenomenal. There are just enough built-in templates to plant some ideas in your head, but not enough to lull you away from the actual customization settings. Color and background customization are organized into two tabs, one being the bigger/more noticeable stuff where you'll want to start new designs. The UI very clearly shows which features are edited by which widgets, and the browser itself updates very rapidly as changes are made. The second tab generally consists of much finer-detail options, like the color of mouse-over sidebar text, etc. Once you've got the hang of it, it might only take 10 or 15 minutes from start to finish to make a sweet new theme - great stress relief.

And then, even better, you can save your own themes and immediately generate shareable links to them for others to download, adopt, and customize themselves! SO RAD!! This app is like a lifesaver in Coronavirus times, when there's so much ugliness and haste - glad we can still take some time out of our rushing schedules just to glitz up our web browsers. Not everything has to be "productivity" all the time!