Patrick Logan has a number of cynical posts up on WS* - check here, here, and finally, here. His observations about Ebay in particular are worth pondering:
Anyone with an incompatible toolkit or language though is not left out in the cold... ebay provides an HTTP and POX interface for each method. Can ebay's approach be considered a success for SOAP and WSDL given this lack of universality?
If WS* were actually easy, and if toolkits were actually compatible, would companies like Ebay bother to maintain a completely parallel RESTian infrastructure?