Not a search engine
After reading this article I went and checked out Ixquick. Firstly, it's not a true search engine in the sense that Google, Yahoo, MSN et al are. It's more a of a scraper, like Scroogle, that appears to submit your search queries to the first-tier search engines (amongst which Google is conspicuous by its absence!)
While it was refreshing not to have Whackypedia articles coming up as the first page worth of results in response to scientific queries (eg "sidereal period of Jupiter"), the results that did get returned seemed to point to mostly commercial sites trying to sell me telescopes or magazine subscriptions or something similar (and that was not from the "Sponsored results" on the page). Likewise, technical/programming queries (eg "php mysql functions") did not lead to php.net, as one might expect, but instead gave me back a page full of links to sites offering PHP solutions for my business at low, low prices.
A few runs with a few different types of search queries produced much the same kind of result. Whether it's because Ixquick is being paid by sites for placement order, or simply because they are using every search engine EXCEPT Google for their results and thus getting the load of commercial trash that most of those search engines dish up, is immaterial. Whether you love or hate Google, its results are still the most useful and relevant of the major search engines.
As for the privacy bonus, that's also provided by Scroogle, which gives you the benefit of Google's relevant search results without the tracking. Scroogle lags behind Ixquick for privacy only in that it only deletes its logs "within 48 hours", rather than never recording the IP at all, as Ixquick does. So if I want to search for something and don't want Google to associate that particular search with my Google account, I'll keep using Scroogle - and I'll be firing off an email to the good Mr. Brandt advising him of Ixquick's no-record policy and suggesting he adopt the same for Scroogle.