It is always interesting seeing stop motion/puppet animation and especially the older stuff. It can be old-fashioned but very charmingly so, have more often than not found it lovely to watch and at its best magical. Mostly avoiding being too crude or trying to do too much. What has been seen of one of the pioneers of it Jiri Trnka's work is really quite impressive and he and his feature and short films are deserving of a lot more credit and international exposure than they get presently.
One of his best short films is 'Two Little Frosts', with only 'Story of the Bass Cello' and 'The Song of the Prairie' being better. Both of which having the extra something that 'Two Little Frosts' only ever so slightly misses. Also consider it one of his overall best, my favourites of his being 'A Midsummer Night's Dream', 'Bajaja', 'The Song of the Prairie' and especially 'The Hand'. 'Two Little Frosts' is one of his most visually striking (standing out also from the visual style usually seen in his work) and one of his most entertaining and really is a must if one is curious as to whether his high reputation is deserved.
'Two Little Frosts' looks beautiful for one thing. Boasting an adept mix of Trnka's distinctive puppet animation for the humans and the bird and some quite haunting shadow puppet animation for the titular characters, accompanied by some quite enchanting and atmospheric backgrounds. The music has also always been a major plus in Trnka's work, and it is typically lush, whimsical and atmosphere-filled.
Furthermore, there is a lot of genuinely amusing comedy, with some smart funny banter and imaginative visual humour (especially the frustrations of one of the spirits with the lumberjack). The story once it finds its groove, after a slightly on the slow side start, is lively and charming.
Also thought that the titular characters were very ebgaging that have great comic timing and their personalities are far from little, actually quite strong. The voice acting is always involved but never becomes too theatrical.
Concluding, great. 9/10.