I bought this because my daugther was on the verge of crawling and I wanted to encourage her. It does what it says and moves around itself. The music and the lights are quite nice (for a kids toys!). It also turns off, a must for the toy box.
The problem is my daugther didn't want to crawl after it - she would look at it go but had no interest in going to get it. She did like the ladybird on the top which you can push around in a circle, but that was about all that she found interesting.
It is also very heavy, so she can't pick it up easily. Which means it is not suited to her favourite activity of taking all of her toys out of the toy box.
She learnt to crawl, without the ball. I've since bought her this Elmer Softball - 10cm
which she much prefers. It is just a regular ball, but brightly coloured. She throws it and crawls after it with much excitement.