Quick comparison: WCF Vs Web Services (SOAP)

	Web Services (SOAP)	WCF
Service Attribute	WebService	ServiceContract
Operation Attr.	WebMethod	OperationContract
Message Attr.	Serializable	DataContract MessageContract DataMember MessageHeader MessageBody
Binding	1 binding – SOAP (XML/HTTP)	Multiple (wsHttpBinding, wsBasicBinding, …) You can implement your own
Transport	HTTP	Multiple You can implement your own
End Points	1 end point (ASMX)	Multiple
Serialization	XML Serializer	DataContractSerializer (Default) You can override the behavior or implement your own serializer
Address format	Http://*****	depends on the binding used
Late binding	Not supported	Supported thru configuration
Hosting	IIS	IIS, Console, Windows Service, …
Authentication	Web application authentication	Username, X509, SAML, Cardspace, custom
Impersonation	Impersonated by Application Pool User	Can be impersonated by current caller. [OperationBehavior(Impersonation = ImpersonationOption.Required)] http://msdn.microsoft.com/en-us/library/ms730088.aspx
Channel Model	Not supported	Full channel model stack – developers can implement any layer of this stack and plug it in thru configuration http://msdn.microsoft.com/en-us/library/ms729840.aspx