The main reason that I joined premium membership was to get access to the additional materials. These have proven to be extremely valuable to me. They have additional content and lessons. However the best part is having the written material so that I can review it at any time. Having the visual media helps me learn the language faster.
I love the podcasts and the easy way that you present the content.
There is probably no way that I would be able to become fluent in Ukrainian without the premium membership.