@markstos It's the perfect companion to #Duolingo - you can ask it to explain Duo's answers word by word or explain your own errors if you don't know what you did wrong.
Or ask it for word lists for a given topic with example sentences in CSV format to load into a training app.
Finally - unlike Duolingo - it knows the difference between Spanish spoken in Spain vs Latin America, so you can prompt it to use the kind of vocabulary you actually need.