There is nothing wrong with Windows 10 per se, but there are many people that are happy with their current version of Windows and do not want to upgrade. For those people, I suggest you take a look at https://www.grc.com/never10.htm?1 and consider installing and following the instructions to block any future Windows 10 upgrades.
If you find you are at the beginning of the Windows 10 upgrade and are presented with the window detailing the license terms, if you click decline, the upgrade should stop. However if you accept the license terms, once the upgrade begins you have to let it finish.
If you find that your computer has been upgraded, you have 30 days that you can restore your computer to the previous version of Windows. To do this, open the Start menu and select Settings. Click the "Update & security" icon and select "Recovery."
If you decide you want to stay with Windows 10, there are a number of things that can be done to make the Windows 10 environment more familiar to you. Contact me if you wish me to make these changes. Keep in mind that if you have old devices or have been running old applications, Windows 10 may not work for you at all.
The free Windows 10 upgrade offer ends on July 29, 2016.