Rated 5 out of 5 stars

Google gained popularity initially because it was clean and lightweight, and now that Google is doing pointless instant searches, being "lite" is DuckDuckGo's advantage, plus privacy like SSL. So if you're looking to boycott Google because of their tax schemes or whatever, this is the version I'd suggest. It's not always as relevant as Google, but you can usually at least find the link to what you're looking for on a top-ranked page.

This review is for a previous version of the add-on (20120418).