It's hard to pick a side here, given then Nintendo were the first to lash out by saying that the SmartGlass tech Microsoft showed off at E3 was a direct reaction to the Wii U, but the slinging match has continued and, like everything else on the internet, we're not far from the point where top executives are flinging "YEAH?!" "YEAH!" at one another through interviews released on the internet.
The other day Microsoft top man Phil Spencer said that the Wii U was graphically on-par with the 360, and that by adding a similar-looking controller and nabbing a handful of games from the 360's back catalogue, that some of the borrowed magic would somehow have loads of people going back to Nintendo. He went on to praise several aspects of the Wii U, but, unsurprisingly, the bit where he said it was the Nintendo 360 seems to have stuck.
Nintendo has responded, presumably thorough a PR rep (given that the original article didn't say who it was issuing the statement, that's a fair presumption), although they've decided just to clarify a little bit in regards to the controller:
"The Wii U Pro Controller is an enhanced version of the Classic Controller Pro that has been designed specially to work with the Wii U console. It simply offers another way to play and more options for developers use. We do not compare ourselves to the other consoles."
No, Nintendo, that's the job of the fans.