Am immensely fond of Russian/Soviet animation, films too but even more so animation, and have been for nearly a decade. A lot of the best of it came from Soyuzmultfilm, some of the best non-UK/US animations coming from them. One of the most notable and prolific artists and directors to come out of the studio being Ivan Ivanov-Vano, though most of Soyuzmultfilm's best work came from other directors in my view.
'Stolen Sun' is one of Ivanov-Vano's earlier efforts and do think he did do better, such as 'The Humpbacked Horse' (1947), 'The Snow Maiden', 'The Twelve Months', 'The Tale of Tsar Sultan' and 'The Battle of Kerzhenets'. It is still very well made and charming, and when saying that it is not one of Ivanov-Vano's best is only because his best work, when his style became more refined and the stories had a little more depth, is so wonderful.
Occasionally the drawing is a touch stiff and things do get (quickly) more interesting when the conflict with the crocodile is introduced after a slightly dull start.
Much of the animation though is beautifully detailed and looks lovely in black and white. That it doesn't try to be too elaborate and keep things simple adds to its appeal. The music is lushly orchestrated and full of character, adding a lot to what is going on and enhancing the little details.
The story is slight and covers very familiar ground, with an outcome that's never in doubt. But that doesn't stop 'Stolen Sun' from being very cute, without being too sentimental, and charming with a conflict that does have some degree of tension without getting over-intense. The characters are engaging with the most interesting character being the crocodile, do find generally that the villain is the most interesting character in cartoons with similar stories though.
In conclusion, well made and more than agreeable. Worth tracking down. 7/10