A recent poll by the Radio Times asked viewers which was the best BBC/ITV children's cartoon/show from the 1950s - 2000s. Despite a wealth of brilliant cartoons from the past, Shaun the Sheep from 2007 - present won the vote. What makes it so popular?
I think there is something about characters that don't speak, especially in animation, when personality and communication comes entirely from facial expressions, gestures, and actions. On top of that, Shaun in a very cute characters, has a previous fanship from Wallace & Gromit, and the show employ lots of slapstick comedy, which is very popular with kids.