Rated 2 out of 5 stars
You get 5 stars for concept, but 2 stars for performance. The blacklist doesn't appear to work. Plus is only lists *.google.com/* as the "website pattern that will be added"; obviously, I'm not going blacklist the google domain.
Secondly, clicked the remove icon (circle with the line drawn through it) has no effect.
So, other words, impossible to exclude websites from custom searching.
Sorry this did not work out, as it is an admirable attempt to do something really good.
Caused by a change in behaviour
this issue was caused by a change in behaviour of the Google Custom Search Result pages. This bug definitely did not exist at the time when V 1.1.2 has been released.
The issue should be fixed with the upcoming 1.2.x release which currently awaits review.