Well, I've given the app 5 stars, because it is just great that it exists and it basically works.
However, there is a number of problems that I hope will be fixed.
1. No feedback mechanisms. Both, regarding usability and tasks. So, if something is not working for me, I have no way to inform the developers (if only here). Or I couldn't find this way.
2. Usability sometimes could be better. It's not always quite clear how stuff works. Like the Perfect Pronunciation section (which is rather important due, because Armenian phonetics is not trivial). Also, I failed to find any options to add friends.
3. Audio sometimes lags.
4. Audio sometimes seems to be absent, despite the presence of the "play" icon.
5. Grammar and word usage explanations could be quite helpful, haven't seen any.
6. Some exercises don't take into account several possible solutions. For instance, many require the explicit usage of a pronoun as a subject, while it is not required by the language.
(7. To use this review as a general feedback platform: it would be great to have a web app for this learning instrument, alongside with the mobile app.)
That's it for now.
That said, I'm absolutely amazed that you've developed this app, it's an immense help in learning this wonderful language. Please keep up developing it.