From personal experience I have upgraded all of the family's devices to Win10 from Win7, 8 and 8.1.
Reality is a very stable and actually quicker operating system than Win 7 for the older machines especially.
Application compatibility is very good and the fact that you can use your older Win95 apps properly at last, through to the new applications from the app store is a big plus in my opinion. You can even get a plethora of Android and Crapple emulator software programs if you feel the need to go to the dark side

.
Yes it is different to what you would experience with Windows 7 but right click over the windows logo in the bottom left corner and all the old features are available. If you for for Lenovo devices, they even have an app that can make the Windows 7 pseudo desktop really look like the older operating system's menu.
One word of caution, go for the latest device you can afford as there are several new hardware features being introduced into Windows base devices that will really be of benefit. I have, for example, a Toshiba Z20t hybrid Tablet Laptop that gives me a genuine 16 hour battery life between charging, yet has a performance in excess of my i5 Processsor based PC despite only having half of the RAM. Some clever tricks for sure.
Remember, as with cars and stereos, you get what you pay for...
Hope this helps.
Colin
Cyprus is heaven on earth.. if there is a heaven that is.