They reduce or eliminate the need for an on-site data center.
They eliminate the need for application administration.
They allow customers to pay on demand for software use, normally on a per-user basis.
They offer application, processor, and data storage scalability.
They offer device-independent access to key applications.
They increase disaster recovery and business continuity.
The biggest concern, or potential disadvantage, is that the data, like the applications, reside in the cloud. Many companies are concerned about letting go of their data. Also, because the company does not own the solution, it can be challenging or expensive to customize the application.