I really liked the book about the crocodile Gena and his friends. I’m on a level of about A1-A2
but learned quite quickly and I enjoy reading easy readers in order to repeat vocabulary and grammar.
I like the fact that there are stress marks, I would say a my fairly elementary level stress marks are essential.
For me the stress marks were the main motivation of buying the books (of course together with an appropriate difficulty)
but I also like the audio that comes with it – often I will first read the texts so I can make sure I know the words and then
listen to the audio.  I can absolutely recommend the book for others learners of Russian.