It's okay. Bit glitchy as you'd expect from any theme configuration addon (eg, breaks lyrics button grayout; sidebar glitch when hid if "menu width static" on; light themes create color conflicts, etc). Makes a few small changes (not really improvements) to Spotify, such as a few fonts and themes that may or may not fit Spotify (subjective opinion), and also "improvements" such as CPU optimization (ineffective, according to my FireFox RAM processes readout) -- and with these very basic changes, seems to justify its
***incessant begging for money every single time you open a new Spotify page. Nagware is a no-no.***

It slightly modifies the Spotify interface, in case you're bored with the default interface, you can try the light themes, where you can blind your eyes and struggle to read the text, as it is not well-formatted at this time. There are no real breakthru features here, such as improving Spotify's increasingly bloated features; removing smart shuffle, say. Somehow, I don't think this is worth the ***begware*** I pointed out. It's okay tho. It doesn't seem to break anything critical, and blocking images/video does reduce RAM significantly (~33%) if you run on a low-end setup (I don't), so an extra star for that, I guess.