Well if you are currently on windows 7, then maybe you should wait a little while longer. Currently windows 10 isn't perfect and it experiences slow shut down times and on some occasions slow boot up times. The OS has just been released recently so it's not perfect.
Go for the upgrade. If your PC is decent and runs your current OS well, it will run Windows 10 fine.
You can follow the Windows 10 thread linked in my signature for steps on how to upgrade.