Firstly, this collection is in Russian. Don't let the English app discription mislead you.
Secondly, as an individual who is interested in history and always happy to find first hand accounts and considerations from promininent historical figures I was dismayed to discover these texts in the original Cyrilic(sp?). More interestingly would be how the creators present an apologist presentation of Stalin's writtings. Which is how I took parts of the app discription to indicate this being.
As for the app itself, it looks rather intuitive from what I could tell. Design is good and well thought out- so for as I could tell given my ignorance to Cyrilic. I spent less than two minutes with it so please consider that, bilangual or polygot people who understand both English and Russian.