Love this!
Nice simple and pretty UI, simple to use, quite practical and more customizable than some other extensions similar to this one.
Widgets have neat rounded design and their animations are a nice, non-intrusive, touch.
I especially love the option to create your custom highlight colors.

Just about only thing I miss here, is a way to assign hotkeys to those custom colors, in similar fashion to those 4 main ones.
(or better yet, ability to override the main 4 colors)

Other than that 5stars!
I'll use this a lot from now on when trying to digest web articles.

Excellent and very simple to use. Thanks !