Thank you! 😄
It doesn't do cross-platform styling well (React Native, React Sketchapp) compared to CSS-in-JS.
It also forces all of your CSS to be static, which I think is often a good thing, but it occasionally gets in the way when trying to build low-level reusable components—having to generate the CSS for all potential consumer states ahead of time is less than ideal.
For a lot of projects, though, these are very minor points, especially since this is also true of all traditional CSS approaches.