It's important to understand that a subject directory will not have links to every piece of information on the Internet. Moreover, every directory is different and their value will depend on how widely the company searches for information, their method of categorizing the resources, how well information is kept current, etc. There is no hard and fast answer to that question. A lot depends on the personal preferences of the user. Some people like directories because the user can control the search pattern, varying the path through the descriptors if another descriptor looks promising.
Directories allow users to browse and to be more vague or general in their search term.
Search engines leave the searching pattern to the computer program and can be used to find more specific resources. A weakness of directories is that you must depend on the descriptors provided by the company. If these are not specific enough for you, then your search may be unsuccessful. As a result, directories can be good for finding general information, but not too successful in locating specifics. Also, the number of resources that you can find in a directory is generally far less than through a search engine.