I found this feature when googling with keyword "google new ceo", visit a result and hit back button on my Firefox. A link shows up "Block all results". Is it good idea? May be yes, may be no :).
In example bellow, I visit link to www.hufftingtonpost.com, and hit back button. Its doesn't mean that news is not good search result, but I want to read more information, and back to Google result. Its better Google give option: block entirely domain or specific link of that domain in search result.
Giving user more control on search result is good. A machine may has "an artificial intelligence", but never ever has "a taste". Google search engine "think" this link has "high relevance" because many user visit it with that keyword. I think, its good idea if Google also give user option what site to be searched as "preferred" site when he/she logged in to Google account. When I logged in to Google account, Google offer me to list my favorite on specific topic, example news: newssite.com, jobs: jobssite.com etc..
Website will compete more hard, they cant fool user with "black SEO". User will help Google to eliminate "useless" website (I often found websites only contain links without any other content, perhaps this what called backdoor site).I believe Google has a mechanism to delete or at least push "useless" website to lower search rank by user help. And user will get better search result. Symbiosis mutuality :).
