I'm just the opposite of AmGaD... I don't feel it significantly reduces battery life compared to the functionality I gain. I leave mine on all the time as well.
A lot of it depends on how many services are using it and how heavy your general use of the phone is. I get 2-3 days out of my 1520.3 charge.
If you have a lot of messaging and Social Media type Apps that are always after your location on a constant refresh rate, that will do you in. I don't have a lot of Apps that use Location on a refresh basis, only a per use basis.