"Most of the Surface reviews have spoken poorly about the device."
What reviews have you been reading?
Edit: Regarding the actual topic, this is just "normal" PR it's a way to scare people into swapping from gmail to outlook.com unfortunately it works better than many might think. Microsoft aren't the only ones doing PR like this it's a lot more common than you might think.
I think PR like this _can_ be good for two reasons: raise awareness of the issue that Google scans your e-mails and make people aware that there are other worthy alternatives to gmail.
I noticed that in one of the "cases" listed on the page by Microsoft one e-mail is about a credit card debt where someone might have overused their credit limit and might be in trouble. The ads that pop up from this is such ads giving advice on how to get new loans to cover the credit card debt which is really not a nice way of helping someone that is already in trouble.
I think that Microsoft could (and maybe should) have less aggressive PR about competitors and just focus on the good parts about outlook.com.
Anyways, I'm probably biased because I love Microsoft and whatever they do and I own all their awesome devices.