In my case, it was the perfect way to learn about some of the important principles that underpin programming, without necessarily realising that it was happening. Scratch just allowed me to be creative with ideas for simple games. You can take away a lot of the cornerstones of imperative programming (loops, variables, booleans, conditionals) but also evented programming concepts; which will make sense straight away in a language like Javascript.
My father is a Head Teacher at a primary school in the UK and has introduced it into the ICT curriculum to great effect. There are primary age children (Overall, I think it's a fundamental stepping stone that children should have the chance to try at school. It represents the opportunity to find out whether you enjoy programming. Until I picked it up, it had never crossed my mind that I might.
Hats off to the Scratch team!