I recently switched full time to Kubuntu because Windows 10 shows Microsoft going down a very worrying path. I.E. Basic Telemetry is not optional in consumer versions. And even more worrying any attempts to disable Windows 10 spying will be reversed by a automatic update see here http://bgr.com/2015/12/01/windows-10-privacy-preferences/
So it seems you are the product in WIndows 10. People like to point out that this is similar to how Google and Facebook operate their web services. Ignoring the fact that those are web services that you can easily choose not to use. Whilst Windows 10 is the dominate desktop operating system that runs your software that you may have spent thousand of dollars on. Not so easy to switch away from that.
They are also doing advertising in Windows 10 as that's what live tiles in the start menu really are. Currently most of them are just cross promoting things like Microsoft's other web services and offerings I.E. Get Office app Get Skype App and Xbox and of course Windows store. But there are also straight up ads right now. Right now if I open the Windows 10 start menu I see an ad for Flip Board, Minecraft, and I heart radio. I assume Flip Board and Clear Channel media paid for those ads.
So here's the deal, Microsoft's monopoly on the Desktop has been historically very bad for users. It's allowed them to produce shoddy software with little real impact on their bottom line. It's now allowing them to go in a direction that will result in a constant barrage of ads driven by data they have collected about you being built right in to the OS. If this keeps going the way it is soon your desktop will look like the TV screen from Idiocracy just a bunch of ads with a little view port in the middle. Microsoft is not trustworthy nor a good steward of this defacto monopoly. It is really up to us tech types to start the revolution by moving to an open platform like Linux where there can be real competition on the desktop between competing distributions. After all we are the ones that have the technical chops to easily move. Once adoption is up better driver and software support will follow. All though personally in my recent switch on a MSI gaming laptop I had 0 issues.
My move has gone without a hitch I am writing this from Kubuntu 15.10 all my daily work is fine. I have VMWare player setup for the Windows apps I need. And when I logged on to Steam thanks to Steam OS there were 107 games already in my steam Library I could install and play. So I have not missed Microsoft's Advertising System Windows 10 at all. It's time to switch.