My daughter has a couple of these now, and thinks they are really great.
They seem to be pretty well made and fairly robust, and the batteries last a reasonable amount of time.
If you use them on a carpet be aware that the wheels can get clogged with hair, I have had to untangle one and it's no fun!
Overall a pretty inoffensive toy that seems to work ok. There are plenty of accessories available to keep the game varied, only your budget will stop you building the collection for your child!!