The thermacell is more expensive than bug spray. But worth EVERY penny. Mine works great. It says a refill kit will last 12 hours but i'm getting about 10 or 11 out of it.
If you move around alot you might want to stick with sprays. But I predator call alot and use it in my stands for mosquitoes,black flys, and it seems to work good at driving the ants away which is a big plus. While big game hunting. I tend to sit and glass alot so for me the thermacell is a perfect fit. Not to mention I hate the feel of the sprays (oily)
Hope this is the info you were after.