You initially get Titles Only but can choose Summaries of the results. Summaries are generally quite good but not always a relevant description of what the site is about. You can also search for Similar Pages off each result, which can be useful. MetaCrawler does a 'parallel search'. Thus, you get a selection of results from some major search engines.
Results can be quite good.
Many smaller search engines use a database created by someone else, which means the owner has no control over what is included in the database. Northern Lights wants to be the most comprehensive and organized source of information on the Web. DMOZ Open Directory uses volunteer editors to build and maintain each category in their directory. Once your site has been accepted into the Open Directory, your site will be listed on partner sites that use the Open Directory data, such as AOL Search, AltaVista, HotBot, Google, Lycos, Netscape Search, etc. They must wade through all that unwanted stuff to get you what you want.