Since this is not an official firmware from Samsung, there’s a chance that this firmware might be unfinished or has some major bugs in it. At the same time, the firmware could be a perfectly working firmware so install it at your own risk. The firmware appears to be specially for the Galaxy S4 model GT-i9500, the international S4 sold as unlocked. So if you have an specific carrier model that’s another risk you’d be taking. Head over to XDA-Developers to download the ROM and learn more.