Public versus Private Interfaces
For the past several weeks I have had my head down coming up to speed on .Net and getting new customers up and running. The most interesting thing I have noticed about being heavily involved in real world large scale complex integration is how we naturally approach interfaces.
For most private interfaces we stay with XML Schemas and essentially REST style interfaces for simplicity and ease of development. For customer facing interfaces we always go with SOAP style web services for formalization of definition and reducing the impendance. If you communicate that your are exposing web services that comply with the WS-I basic profile it eliminates a lot of discussion. Similarly if we consume services that are defined the same way it reduces discussion.
Perhaps REST versus WS is really about private and public interfaces.