This sample shows how to use the Sentiment Analysis Middleware in your bot. In Startup.cs file, you can choose the Middleware to work with either Cognitive Services or ML.NET based Sentiment Analyzer.
Currently, it will only return a score (from 0.1 being negative to 0.9 or 1 being positive).
In case you have any suggestion or you would like to see more features on this, please let me know either here or on twitter!