We've now been using micro:bits with our Code Club students for three sessions (6 more to go until the end of term!). We've had 20 kids come this term (ages 9-10).
It's been really successful! The kids love using them and need very little motivation to keep working on projects. I feel there's been a lot less distraction compared to using Scratch and a deeper understanding of how the code works. The two most popular projects we've had so far are Fortune Teller (i.e. magic 8-ball) and Frustration. We've heard a lot of laughs as they ask the fortune teller questions and it's been great to see the kids get an easy introduction to electronics.
A few kids have found the sound blocks and played with them and they've learnt how to connect their headphones using the dragon clip leads.
We've been using a leaderboard which has been useful for two reasons: