What are the advantages of expert system?

1. Lacks common sense needed in some decision making
2. Cannot respond creatively like a human expert would in unusual circumstances
3. Domain experts not always able to explain their logic and reasoning
4. Errors may occur in the knowledge base, and lead to wrong decisions
5. Cannot adapt to changing environments, unless knowledge base is changed
6. Expert systems can't draw analogies from other sources to solve a newly encountered problem like a human would, in other Words they can't be creative.
7. Human experts automatically adapt to changing environments; expert systems must be explicitly updated.
8. Human experts have available to them a wide range of sensory experience; expert systems are currently dependent on symbolic input.
9. Although inexpensive to operate expert systems are expensive to develop and maintain.

The advantages of expert systems are "applications that combine computer equipment, software, and specialized information to imitate expert human reasoning and advice." So the advantages are that all of those can be combined as an application.