Buy a kinect or not. that is the question?

I ve been interested in the kinect since it came out and I'm just trying to see if its worth it. The only problem is the only game I want is dance central. Sure kinect sports and all that stuff is fine but basically just want the voice controls , dance central and yourfitness. Is the kinect worth it. Also how much room do u actually need to play. My room is quite spacious but how much is needed