I'm not using it in my business yet, but I created an IoT project to test the Watson text to speech API for the Renesas IoT Sandbox. See this. http://learn.iotcommunity.io/t/using-speech-in-your-iot-proj...

It's actually easy to use the API and I'm hoping to use more features for the my next project, which is a mobile app to get voice alerts of distributed IoT data from the cloud. Not sure if this answers the question, but I think the API is usable by businesses.