My Feedback
First, there seems to be no provision for user registration or authentication. I see no option for a user profile to be created. This means there can be no synching of progress from one device to the next.
Second, even in the “elementary” level of this app, the grammar and discussion labels are in the target language (in this case Spanish) rather than in English. It would be helpful if this app could provide labels in both languages.
Third, I see no “help” option and no way (either within the app or via email) to send feedback, report glitches, make requests, or simply to ask questions.
Fourth, and lastly, while subscription plans are great for many people, I would prefer a single-payment (lifetime) option. In this age of streaming content, to monitor and manage subscriptions is a huge chore, and a lump sum payment would be a big help. (Babbel, Rosetta Stone, Rocket Languages, Pimsleur, Lingopie, and others offer this as an option.)
As I have said, this app looks very promising. The developer is obviously putting a lot of work into the app. It’s well designed, and the content appears to be good. And I think it has a bright future in a highly competitive field.