This is just... creepy...
I'm not 100% sure why and I had to watch it a few times before I even realized it was creeping me out... But once I figured out why it was distracting/disturbing me, I realized it was just subtly creepy. It's probably the dark colors the guy is wearing in juxtaposition with the all white background. He looks shady. He doesn't look confident. He looks like he is sneaking. When he walks over to the camera he has to bend down to summon you (It would feel less creepy if you were always at eye level). It feels like you are a kid and some stranger is walking by and bending down into your face and saying, "come on kid, come look what I've got". He's got his hand in his pocket... why? That's creepy. This whole thing feels like a drug dealer trying to get me to come smoke pot/crack/whatever with him. It's just... creepy. Yuck.
Sorry Microsoft... but... FAIL.
Here's the whole ad (I was able to extract it from this page)