Last modified: 2014-03-19 19:34:58 UTC
Bug 23141 is on the icon itself, but some think that the hover text, supposed to explain the feature, fails its purpose:
(From comment bug 54730 comment 15)
> On the other hand, the star itself doesn't even tell people who are logged in
> what it is unless they hover, which frankly isn't very good for something
> that's such an important part of the interface...
The current hover text is "Add this page to your watchlist", which indeed doesn't explain anything: it's just a tautological definition of the word "watchlist" which used to be the label of the button.
Maybe there's also some way to make it more obvious that one can and should hover an element?