What do you like best?
vCloud is backed by VMWare, the company that brings the gold standard for virtualization that most all companies utilize in their data centers. vCloud takes the experience and knowledge of VMWare one step further and provides a platform familiar to companies in order to extend their infrastructure to the cloud with minimal configuration.
What do you dislike?
As with any hosting platform one pays a premium for the VMWare name, especially when it comes to scaling out virtual machines and resources in the cloud. Pay careful attention to pricing on network bandwidth and storage to ensure the cost of vCloud is in fact cheaper than hosting your own infrastructure.
What business problems are you solving with the product? What benefits have you realized?
vCloud makes for a great platform for hosting active directory, email, and web services as well as federated active directory services in the cloud. Solutions have been realized as well hosting CentOS linux servers for short term, high availability projects.