Made the switch over to Win 10. Nothing is on fire or covered in bees yet.
Make sure you turn off all the nonsense in Settings - Privacy and set data collection to "basic" since there's no "none" setting. It's hard to turn off Cortana, but you can turn off her data collection pretty easily and stop her from listening to your mic if you have one. I had to make a local account to stop the personalized ads. There's a setting here you can turn off, but I find local accounts are safer. Then of course there's the Digital Advertiser's Alliance Consumer Choice Page that lets you opt out of data collection for 128 companies.
Hmm, I should probably come to a decision pretty soon as to whether I want to upgrade to Win10 or not.
Information collection is like mining for gold these days, and that's basically all Windows 10 does. There are only a few nice features it has over 7, but 7 will be discontinued before long in favor for these profitable upgrades so you might as well while it's still free.