The demo they show has an excel sheet source being transformed into another sheet by grouping by a specific column. I don't like how it does a transformation step, sends a new transformed file and then switches the display to this new file. I worry that this loses the history of what exactly has happened to the file, so you're letting a black box run an unknown transformation and trusting the result to be correct.
A better implementation would require a custom UI for this, similar to existing data wrangling tools where every action is logged so that it's clear what has happened to the file and the steps can be checked transparently and rolled back if needed. As it exists now I would find it hard to trust it