Yes, all services include a feedback API, and the demos also include a mechanism for providing feedback. As an example, see 4th paragraph in this doc, which also includes a link to the API docs: http://ibm.co/1yNfztF
And here's a link to the demo, see the "Give us feedback" link: http://bit.ly/1EJllDF
We want feedback on all our services. If you are speaking about using data to update the service, I know the speech services do not yet have this capability.