Hmmm, when broken into it's most basic form, the op reads:
"I saw someone play Kinect and think it sucks. So just admit it sucks like the Wii did at launch, okay?"
Interesting way to form a question IMO...
Regardless, I have had Kinect since launch; I have used or watched people use Kinect Sports, Dance Central and Adventures in one-on-one play and party situations.
The simple straight answer is, the hardware works - period. IT's not without it's quirks or idiosyncracies, but it does work. In party situations I had people of all ages slipping into and out of Dance Central and Kinect had no trouble with the switching.
On top of that, it's fun - when people are playing, they are having fun, you can tell.
All that being said, Microsoft and their partners have to deliver consistent software to keep it's owners engaged or it won't matter how much it does work.