I gave my 8-year-old a subscription and it has been great. I only did a tiny amount of electronics in high-school and both of us have learned a lot. The crates come with everything you need (and a few spares in some instances) and the instructions are clear.
The fact that it addresses both the electronics and how programing a UNO interacts with it is particularly useful.
We had some difficulty getting the UNO to work with our older iMac (which was frustrating) but that is nothing to do with Creation Crate. Works fine with our newer computer.
I would highly recommend it (and do) to anyone with an interest in electronics and or programming.