I updated to Windows 10 from windows 8.1 recently. It was a free update. Some people are very much confused whether windows 10 will work fine with their machine or not.
Please leave the confusion back and go for the update. It works very well in my basic laptop. Mine is a 2 GB ram, Intel Atom processor laptop(Asus Eeebook). So if you are having a same configuration computer or higher, you can definitely upgrade to windows 10 without any doubt.
I have some problem with my WIFI driver. It gets uninstalled automatically 3 days once. So I have saved the wifi driver setup in my system and whenever it gets uninstalled I will install it back. Microsoft will release some updates in near future and this bug will be removed for sure.
I also heard some people telling that Microsoft gave windows 10 for free just to steal your data from your computer. Ohhh come on guys. Microsoft is a giant. It have nothing to do with your vacation pictures and Bollywood songs stored in your hard disk.