One additional point specific to Spark 2.0 - for the alpha Structured Streaming API (only), the file sink only supports Parquet format (I'm sure that limitation will be lifted in a future release before Structured Streaming is GA): "File sink - Stores the output to a directory. As of Spark 2.0, this only supports Parquet file format, and Append output mode."
http://people.apache.org/~pwendell/spark-releases/spark-2.0.0-rc5-docs/structured-streaming-programming-guide.html#where-to-go-from-here