the thing I've found teaching is that the place scratch really shines is teaching kids who are a bit too young to "get" Python. I think it's related to their language/visual intuition but a seven year old will be able to pick up quite complex things in Scratch visually without being able to grasp fairly basic things in Python. Give them a couple of years in the oven with or without Scratch and they'll be much more confident and ready in picking up Python, but scratch can teach them a lot in the mean time.