Having a heat protector is better than nothing at all. With this, you can tell the iron is burning the product off than your hair, because of the steam coming off from it. I don't straighten my hair all the time, but it's difficult to say if this stuff really does protect my hair.
My hair does end up frizzy after straightening, but that could just be due to my straightener. However, this stuff does make my hair less dry than not using it at all.
Frizz and split ends were becoming a consistent thing with my hair. I was talking to my hairdresser and we couldn't figure out why my hair was becoming fried and sad like, until I mentioned that the machine I work with daily pumps out 70°C heat. DA-DING! Even thought I don't blow dry or straighten my hair, it was still being fried daily! Since I found this product it has kept the moisture in my hair and stopped my poor hair from being abused by my working conditions!
Tips: Don't only think of heat damage from hair styling tools alone, the sun and other forms of heat can be JUST as damaging :)