I must say, I find it difficult to work with longer (couple of pages) texts, as the buttons are on top of the interface and I need to scroll up and down a lot.
But the biggest problem: Is it veeeery slow? When I select a paragraph and choose "expand" or "rewrite", it takes several minutes to produce any text. Sometimes longer, at which point I closed the text.
I tried this yesterday and today, with similar results.