ClearDB Competitors and Alternatives

What do you think of Amazon RDS?

Pros: Very easy to start with. No need to mess around with OS requirements. All infrastructural issues are handled automatically; backups, patching. Cons: Some features are disabled, like running "alter system/database". There are Amazon alternatives, but it is not transparent to the application. When migrating an existing application, it should be adopted. Also, using these Amazon alternatives produces "cloud-lock", since they exist only in AWS. Some database components are not available. Most remarkable is the absence of RAC.