Segun David Chappell :: Blog,: las dos tienen su lugar, para los diferentes tipos de aplicaciones.
A RESTful approach is a natural for data-oriented applications that focus on create/read/update/delete scenarios. Lots and lots of apps fit this model, especially on the public Internet. A solution based on WS-* makes more sense for service/method-oriented applications, especially those that need more advanced behaviors such as transactions and more-than-basic security. (Doubt this last point? Look up "Security" in the index of the Richardson/Ruby book: Exactly one page number is listed.)