I am a childminder so bought this as an activity to do with a range of children from 2 upto 11 years.
It is really terrible. Ours has been going for about 4 weeks now (the max time wormworld say you should keep the worms in for) and you would not know there were worms in there! Although the box is quite thin, the worms still manage to stay 'in the middle' and so out of sight.(there are worms in there, 9 in fact, 10 is the max number allowed) Aload of cobblers and a complete waste of money.
Their is a tiny booklet in there telling you about worms, which is slightly interesting, but by far the most enjoyable part of the whole thing was digging for worms in the first place. You would be better off saving your money and getting an old bucket.