I have been using the It's A 10 spray for about 6 months, and it is finally almost gone. It really is a great value, since you need to use only a tiny amount to see results.
This is a great detangler. If you like to comb your hair when it's wet, this stuff will make the comb glide right through your hair. It also does a great job of reducing frizz, as advertised. When I use It's A 10, my hair is very soft, shiny, and smooth when it dries.
I can't comment on the heat-protecting ability of this spray, since I don't blow dry or straighten my hair. (The horror!) I imagine it would work well, since it contains silicones and parabens. These ingredients make hair smooth and silky and allow flat irons to glide along the hair easily, reducing the time needed to straighten and therefore (theoretically) causing less damage to the hair.
One word of caution: If you have fine and/or thin hair, you may want to skip this product. It's quite heavy, and if I use any more than a couple sprays, it makes my hair very limp. If you do have fine/thin hair, start with just ONE spray, distribute it with a comb, and see what your hair feels like. You can always add more, but once you've put too much in, there's no going back.
Also, don't expect great results from this spray if you use natural or organic shampoos that don't have sulfates. Those shampoos aren't strong enough to completely remove silicones, so you may end up with a lot of build up, which can also result in limp, lank hair.
Finally, please be aware that no product can repair damage. It's A 10 does a great job of making hair LOOK healthy, but it cannot seal split ends or reverse damage from straightening or dyeing your hair.