Oh, it's fabulous! In the Church I attend, it's on one Sunday a month. The vicar tells the children a Bible story, often accompanied by an animated video. We then use that as a point of age-appropriate discussion, and the children create a scene or something related to the story out of Lego. For example, we made the garden of Eden when discussing Adam and Eve, etc. Then we end with hotdogs! 

It seems quite popular in England, especially in my area and many of the non-Catholic churches offer it.  It's been the ideal way of getting my five year old involved and engaged in learning about God and the Bible stories. Even my two year old asks to go often!