I watch Netflix and Hulu + using my Xbox+Kinect with a DSL link, which saves a lot of money compared to Comcast, the cable TV monopoly in my area, which I used to use until six months ago or so. My observations:
1. The Kinect is a detriment to my TV watching experience, not a benefit. About once every 2 or 3 nights, the Xbox will start fast-forwarding or fast-rewinding for no apparent reason. The Kinect software did it, either because my wife or I said something it interpreted as a command, or because the actors on the TV commanded the Kinect to do it. I'm told the Kinect software attempts to subtract the Xbox's audio output from the room's environmental sound, in order to prevent the latter; but in my personal experience it seems to happen sometimes anyway. I know it's the Kinect because my wireless controller turns itself off after a few minutes, and it's always off when this event occurs. By the way, the event does suck; it's not minor. It takes about a minute to fumble with the controller to turn it on and rewind to where we were. We don't use voice command for this because my wife and I are usually shouting or throwing things at each other, and voice command isn't amenable to panic situations.
2. I love this setup for the ability to watch our favorite series one-after-another without waiting a week for each new show. However, now that NFL football season has started, I miss football. A lot. The PS3 we also have next to the TV has a new NFL Ticket option, I'm told, but it's over $300 for the year, which I can't afford.
3. More minor point: About once per week, the Xbox used to display an unwanted Kinect UI at the bottom of the screen in response to me stretching my arms out, shifting my position, or otherwise moving a little whilst sitting on the couch. This problem was unintentionally fixed by my wife when she actually rotated the Kinect to point away from us, and to point right at the wall, because she is sure there is some network hack available that will let strangers use the Kinect camera to spy on us as we sit in our living room. (Yes, the kids rotate the Kinect camera back to face them when they play Kinect games.)
Although point #2 is the most pedestrian comment above, it's the most important one. Content is the killer app. Not voice command while watching TV. As msobkow posted above, I, too, have always heard complaints about being able to access content, and I have never heard anyone complain about not being able to use gestures and voice to control their television.