Windows 10 is a more secure, reliable, and feature rich O/S introduced so far.  Users on recently purchased systems are likely to benefit the most.  But there are some considerations where users on older equipment or software may wish to stay with their current older software.

http://www.pcworld.com/article/3092365/windows/10-reasons-why-you-shouldnt-upgrade-to-windows-10.html

The clock is ticking, folks. If you want to upgrade to Windows 10 for free, you only have until July 29, 2016 to do so. And most people should! Windows 10 is  the best Windows yet, chock full of handy new features, sleek  under-the-hood improvements, and  headache-killing extras.  But it’s not for everybody. There are some very real, very valid reasons not to upgrade to Windows 10.  If you’re on the fence about whether to accept or reject Microsoft’s freebie, read on for some concrete justifications for staying put.

1. No Windows Media Center or DVD support
2. No desktop gadgets or widgets (Win 7 feature)
3. No OneDrive placeholders (Win 8.1 feature)
4. No control over Windows Updates (only minimal postponement)
5. Privacy concerns (aggregate data sent to Microsoft)
6. Ads and more ads (Skype or Office upgrades)
7. Microsoft’s aggressive upgrade tactics (some WIN7 users disabled updates)
8. Software compatibility (XP compatibility mode disappears)
9. Hardware compatibility (Old scanners, printers, wi-fi connectivity)
10. Ain’t broke, don’t fix it (some users may not wish to learn new O/S and UI)