The concept certainly isn't new, The playstation 2 with the eyetoy was the first console to introduce controller free gaming using a camera. Of course the technology is now updated with the xbox360, but is it worth 130 pounds?
To be quite frank no, most commentators are hoping firmware updates will fix the faults, unfortunately the kinect uses a very low resolution sensor, so it will never get better at sensing / detecting, firmware cant upgrade hardware. It will always be quite imprecise and will always be quite laggy. The camera itself apparently costs around 35 pounds to make, so there is quite a heavy mark up for the price as well.
There is a reason both Nintendo and Sony turned this technology down, you are the controller, but with no controller you are left to run on the spot to actually run you have no buttons so have no way of firing weapons or using tools.. Its great for dancing and excercise, for anything else its mediocrity at its finest and will probably drop down in price quite heavily after christmas.