Tempered glass is more heat resistant than regular glass, meaning your phone is less likely to be damaged by heat. Plastic screen protectors are much more likely to get scratched than a tempered glass screen protector, which are up to five times as thick than standard plastic protectors. 

The smoothness and clarity of the tempered glass makes the screen protector feel more like your actual smart phone screen than a plastic screen cover would. Tempered glass screen protectors are also a lot easier to put on your phone than a plastic screen protector.