Awesome, simple game. My 6 year old is glued to this game. He can easily solve the early puzzles, needs a little help past level 15-20. My husband and I enjoy it, too. No speed involved, just brain power. Take your time on each level, try again as many times as you need to solve a level -- there is no penalty for mistakes and taking your time. You can even redo levels as many times as you'd like to see if you can come up with a better solution.
The downside is that the instructions are minimal, so it's hard to know what tools you have at your disposal. There is a demo video on the CPD website that helps.