I like the physical dice too tbh if only cos it helps encourage that face to face interaction so many of our kids find hard.
Personally I think you'd lose the opportunity to maximise the potential giggles social skills benefits if you restrict use to the electronic app. It's been nice to see DS's friends sat around a table like wot we old uns used to, back in the day TALKING, instead of sitting around a console game this half term. (that last comment goes for his NT friends too btw!)
I also like the fact that the basic set is ideal for popping into a pocket for family visits etc.( I think we'll get enough mileage out of the orange box not to need the extra variation sets if I'm canny 
) We'll take ours when we go camping as a good "rainy day" activity".
So far we've worked our way up from constructing a sentence using just 2 dice at a time to short descriptive paragraphs. I think for just a months worth of use, every 2 - 3 days or so that, that is FANTASTIC progress for an articulate but inflexible thinker like my son, who used to freeze in fear at the mere idea of coming up with a short verbal story from his own imagination.
Try
Choosing a "theme" for your story - eg "In the forest", "In Tudor times", "lies versus truth", "the value of friendship" etc
Starting with a "standard" fairy tale sentence - eg "once upon a time"
Taking it in turns to concoct the next sentence for a story.
Telling a story totally in the past, present or future tenses
Gotta be honest I'm using it totally from a "silly games" perspective for the moment. I figure the best learning is done with enthusiasm and a chortle, so we won't apply the dice to formal literacy work for a few months or so. At the moment DS sees it as just a bit of fun. I suppose I'm trying to ensure we walk before we run with the concept really as I'm not a SALT.