Should i upgrade to Windows 10?

I have a Pc with a Core 2 Duo processor 2.66GHz , 2 GB RAM and 500GB HDD. I have Windows 7 x64. But from several months i have that little icon on system tray that suggest me to upgrade to windows 10 that is free until july 2016.

Should i upgrade to Windows 10 ? Will i gain or loose from this upgrade ?

Thank you !