I just got home and put batteries in and then turned it on and nothing happened. I then realised that you are supposed to press the nose which is a good idea. It is really fast and the detail is great.
There are 2 problems!
1- The wheels are really obvious and lift it off the ground when in the episode they glide across the floor.
2- It is really small! I didn't expect it to be the same size as the episode but not that small. I was thinking it was be about the size of the 11th Doctor's screwdriver, but no. It is smaller than River Song's screwdriver!!!
It is however a great prop replica and it is really cute. I hope they release one where you can see the teeth and also a remote control one, I would get both