Advantages
A one off fee for the software - no further budgeting required.
Huge number of records available, and each record is a free download.
Through a selection of target servers, the searcher can narrow the type of library searched, making the search more specific.
The records gained are usually recorded by professionals International records - no regional limitations.
Disadvantages
Reliance on the internet
Records may have to have some modification before being loaded into the local OPAC