Text based navigation menus are very effective on a number of fronts.
First, search engines love straight text. A navigation menu will often contain words that the search engines will pick up on. Keywords that are pertinent to the theme of your Web sites and ones that may often be searched for frequently by users of the search engines.
Secondly, a well designed text-based navigation system can provide an uncluttered, simple way of navigating even the largest Web site. Many high-traffic Web sites use text based navigation menus over graphical menus for this very reason.
Thirdly, standard text based menus use less code than a graphical menu system, which means that the page will often load slightly faster. In these days of broadband Internet connections, this isn’t as important a factor as it used to be, and the overhead of a graphical menu system really doesn’t add so much that the load time will be noticeable by anyone other than people on a very slow connection.