Another quick extension method to help with getting a sentiment score from a RecognizerResult;

public static double? GetSentimentScore(this RecognizerResult luisResult)
{
    double? result = null;

    if (luisResult != null)
    {        
        var data = luisResult.Properties["sentiment"];
        var sentimentValues = data as IDictionary;
        var score = sentimentValues["score"] as JValue;
        result = (double)score.Value;
    }

    return result;
}