It's actually not a search engine. It's called a metasearcher--it uses Google, Ask, Yahoo, and Bing to optimize searches. Overall a superb and useful site.
It seems to be a pretty good site. Just DON'T download the toolbar. It installs something called Trackware.Dogpile. When you type a search on this toolbar, it redirects you to clickit.go2net.com , and in turn sends you to a target site. Basically, if you have the TOOLBAR installed and search, a lot of computer information will be sent to them. If you want to use the search service, thats probably safe enough, just DO NOT download the toolbar.