It's always seemed as though Google's and Mozilla's relationship would weaken over the years, though honestly I expected Bing rather than Yahoo to be the one to step up and fill Google's shoes. Also surprising is that apparently Mozilla was the one to initiate the switch.
As a Firefox user, all in all I'm rather pleased. I've just tried a few of my typical searches on Yahoo and though the expected links aren't the top results (seeing links for Rust-the-game instead of Rust-the-language...), they're on the first page. Let's see if that improves with time as I use it more. And I'm happy to support some more diversity in this space.
As a long time Mozilla lover, I have been quite concerned about their dependence on Google for quite some time now. I'm really thankful that they have had the courage to cut ties. Must have been a scary decision.
It uses the Bing index, but there are at least some differences in how it retrieves and prioritizes results. (If you run the same search on yahoo and bing, even with fresh cookies, you won't normally get identical results.)
Yahoo may do some spidering of their own as well, although not to my knowledge. I know at least the above is true though. Also as an aside the Yahoo BOSS API is significantly more powerful than the comparable Azure Bing web search API. Unfortunately, they also just doubled the access price this month.
As a Firefox user, all in all I'm rather pleased. I've just tried a few of my typical searches on Yahoo and though the expected links aren't the top results (seeing links for Rust-the-game instead of Rust-the-language...), they're on the first page. Let's see if that improves with time as I use it more. And I'm happy to support some more diversity in this space.