I bought this for my six year old, who wanted a black one specifically. Who knows why?
The Crab looks good, but makes quite a bit of mechanical noise, as if clockwork. It makes its way slowly across the floor, sometimes randomly changing directions. It does change direction on a hand-clap, about 50% of the time. When it gets to a relatively dark place, it stops moving. It seeks inactivity. My son played with it for 10 minutes and then found something more interesting, and I couldn't really blame him.
I happened to buy a proper mechanical wind-up crab for our other son, and we had just as much fun, but wih it costing £1.50. Hexcrab is great if you are interested in expensive toys - but I recommend you save your money.