I don't think they are good, but since my expectations were very low anyway I wasn't really disappointed.
I remember some days ago I criticized a Kinect Sports ad because it shows pretty much only game footage and not people playing the game. Well in that regard those ads were a lot better.
The first one had the children cuteness factor, but apart from that I think it was rather lame. Simply because what we saw the children do (waving your fingers and lying on the gound) did not at all remind me of interaction with a pet.
The second video looked a bit more fun, but in contrast to the other two videos the problem of being forced to stand instantly came into my mind. The actors seemed like being nailed to the ground and I saw no good reason why they had to stand.
The last video would be the one most likely to catch my interest, even though most of the gameplay (=running in place) did not seem to be long fun either. Football was the only sport this ad would make me interested in trying out.