We started off exposing REST APIs to other business units and our external partners by doing legacy integration.
The Gateway is a security control point and a way to drive standardisation.
Live API Creator is used very successfully by one of our businesses to run all their APIs. Other BUs use the Live API Creator to create the easy, "quick win" APIs, which do not make sense to host on the ESB or where resources are not available to do it quickly.
We handle some SOAP services where we are only interested in adding additional security and metrics on top of the SOAP services. We even transform JSON REST to SOAP where legacy internal ESB systems are not able to use REST.
We have seen a huge uptake in routing messaging services, like SMS and WhatsApp. The Gateway currently serves to standardise these into a single API view with multiple channels.