I would say that price is a major disadvantage, because the Kinect sensor costs almost as much as the console itself. That's why I don't own a Kinect; not only can I not afford that much money, I keep thinking that if and when I have the money to spare, I could just save up a little bit more and buy a whole other console.
I agree. It is a rather pricey device. I don't even understand why those sensors cost so much. My brother says the Kinect is worth every cent, but I have my doubts about this, considering that the games available for it are in such a limited number.
The Kinect is fun to play but it could take a while to get used to. It's not the same when you are playing a game without any controller at all. There could also be times when some of your movements are not recognized by the device. It's great for some genres like dance games and exercise games but it's not a great fit for others. Imagine playing an MMORPG with Kinect, or Halo or Gears of War or Mortal Kombat? You won't have complete control of your character while playing these games.
One big disadvantage is placement. You have to place it just right or your motions may not be fully detected. It has to be viewing you a certain way, so you're going to need something like a TV cabinet to place it on.