I upgraded to Windows 10 successfully without any issues and my PC is running very smoothly like a newly bought PC. Just one thing to keep in mind that after installation of Windows 10, the screen will appear stretched due to some issue with the display drivers but it is not any issue to worry about. Just go to 'Settings > Update & Security' and check for updates. Windows will automatically download required drivers for your system which will make display look perfect.
Enjoy using Windows 10!!!!!!!!!!!!!