The game will only be free if you use the Kinect Central app to download the game. Though far from a critical success, the 800MSP Kinect game maintains a Metacritic average of 70. It's not great, but it's quite a bit better than the beating our reviewer doled out to the latest Kinect game: Steel Battalion: Heavy Armor.
Haunt is something like a family horror (read: not horror) adventure game with players exploring a haunted mansion by walking about, picking up objects etc. You may not have heard of it many times before, but it was created by PaRappa the Rapper dev NanaOn-Sha and Zoë Mode (Singstar).
So maybe it's not Child of Eden, but a free game is a free game. Haunt will be available free of charge through July 2nd.