So, since no one wanted to buy my bottle, I decided to try it out. I've noticed of late that my hair seems to be even finer-textured than usual--curls are less resistant--barely able to hold a curl pattern, so that tells me that I probably don't need a strong keratin formula anymore.
I definitely smelled a little different--not in a good way. All in all, the results were about the same on my hair; it's hard to tell because I only use it on the new growth roots.
I don't know how well this would work on coarser hair--depends upon what kind of look you're going for--but it seems to be fine for fine hair.
One thing remains constant--fine hair SUCKS, and keratin can't do anything about that. In fact, it makes it worse, so fine-haired ladies, proceed with caution.