I'm using the iPad to study Italian and there is an inconsistency with how the program works. The text windows in "Write the Words/Phrases You Read," are stationary, while the text windows in Write the "Words/Phrases/Conversations You Hear," shift up to enter text. Correcting typos while chasing a moving text box is frustrating. I would like to suggest that "all" text entry boxes made stationary.
There should be an index of subject matter, so we can go back and review topics, grammar, vocabulary, and so on.
Navigation, at least on the iPad is clumsy. A set of nested grids would make it easier to find what you are looking for. For example, Italian shows as five boxes, then selecting one, shows a list that you have to scroll through. It would be easier to navigate if it showed a grid of thirty lessons, then show the options download, info, stream within. There should be some sort of "real" book marking (rather than the sliding bookmark that moves as you progress) and notation capability, so you can mark and identify sessions that you think you need to review.