The Apache Solr Search module adds a lot of functionality to the base Drupal system. You can easily search by title, body, and CCK fields. One you'll often run into is many times the designer and/or client wants CCK field data in the search results. You can easily search, and filter by the CCK fields, but how do you get them back out of the Solr index to display? You could do something extremely inefficient like running node_load() for every returned node ID, but there are better answers.