We have been playing with the MakeDo for about 6 months and can't say enough good things about it. My son is 4 and we make cars and fire trucks and rockets, etc together out of our garbage/recycling. Paper plates become steering wheels and tires, egg cartons become control panels- it is awesome! It is best enjoyed with other children - we have used it several times for play dates and play parties, and ALL the kids go nuts over it. Supervision is required. You can deconstruct the creation and reuse all the MakeDo pieces. You have to squeeze the bendy part, and the connector tail will release (if you just force them apart, the tail will break). My 4 year old can connect the pieces, but is not able to take them apart by himself. It isn't a big deal because he is mainly interested in building things.
Overall, I am crazy about the MakeDo, and have just bought more sets to give away for birthday presents.