I am going to dispute the notion right now after the calm of a $500 million advertising campaign for Kinect that Kinect is successful on it's own merits, not just the advertising.
Looking at the sales numbers, I agree Kinect is successful. However, numbers are not generated in a vacuum independent from other variables and I am old and wise enough to look at other factors.
Looking at the sales numbers with the advertising campaign, I cannot honestly say Kinect is successful because it is intrinsically better than the Wii and Move at the moment. I firmly believe Microsoft threw everything and the kitchen sink in with Kinect, thus they are reaping the rewards of a good gamble.
This being said, I don't think we can honestly say Kinect is successful until a year after it's release. Microsoft ain't going to keep pumping in $500 million in advertising for Kinect every quarter of 2011. Thus forth, for me, it is a wait and see game depending largely on how Kinect does during the slow months to render an opinion on whether Kinect is truly successful because it's own merits deem it to be or whether a large part of it's success was tethered with a $500 million advertising campaign.
As for Nintendo, they need to focus on the 3DS and building relationships with 3rd party developers so that when the Mii drops, they will have sufficient relationships to not only dominate with their usual Mario, Donkey Kong, Zelda, and on, but more mature titles to siphon away the steam from both Microsoft and Sony.