Upgraded my HP laptop a couple of days ago from Windows 8.1 to Windows 10. The entire process including download took about three hours from start to finish and was fairly straightforward. In fact, if you select the default options for everything, it is entirely straightforward, but then you authorise Microsoft to essentially monitor everything you do on your computer for ever.
Take a little time to check the small print on the settings screen, do you really want your computer tracked so that geographically appropriate adverts can be displayed? Do you really want copies of everything uploaded to the cloud? Do you really want all your enquiries to be logged and analysed to provide quicker and more specific responses to your queries?
If you have a Windows phone, tablet and PC, then upgrading to Windows 10 makes absolute sense and enables all of your devices to synchronise files.
If you are running Windows 7 the case for upgrading is less clear cut. You will need to obtain a third party media player to burn and play DVDs and CDs and commercial programs are not particularly cheap. The well loved solitaire programs are replaced by new versions which are less attractive to use in my opinion. If you have copies of the files from an older version of Windows, they can be copied and pasted into the appropriate directories of Windows 10 and they will still run. Esentially the cards.dll file is copied to the system directory and the sol.exe file and other solitaire game files you want to the program file directory and just make a shortcut to sol.exe (and other games) from the desktop.
All the other programs and files you have installed in your computer remain unaffected and just work as usual once you have completed the upgrade.
You may need to download new graphics driver files before Windows 10 will invite you to upgrade, provided you have the little Windows flag in the toolbar at the foot of the screen. I had to download the new screen drivers before the Windows update message moved passed the you will be notified when your update becomes available stage.
So if you are running Windows 8, upgrade immediately and lose that annoying jump into the tiled screen from the desktop everytime you move the mouse to the top right of the screen. Worth it just for that.
Windows 7, Meh! Probably best to just carry on using that, unless you need some Windows 10 feature.
This is by some margin the least eventful update I have done with a Microsoft operating system and I have been through every one since DOS 3.0 including Windows 286!