I have used Uncurly twice. The first time lasted about 5 months. Completely loved it. Keratin changed my life--my hair went from being an embarrassment that I was always self-conscious about to looking great all the time. So I knew I would keep using it forever, but it cost me $400 each time I went in. I'm a nurse and three of the gals I work with used this and loved it, their hair looked great, so that was enough proof for me. I can't tell you how happy I've been with it, and above all, with the money I saved. I had used two different at-home keratin (ha!) products before--don't remember their names, one was from Sally's and one was from CVS, and both looked good for 3 days so I got excited, but once I washed them out, my hair was back to usual. No change, which was frustrating after I spent the time carefully ironing them in.
I should also say that Uncurly makes my hair smooth to the touch, which I have NEVER had before, since it's naturally coarse. The humidity resistance is superb. I mean, nothing will totally block it when there's visible steam outside like after a rain in the summer, but the effect is so minimal now, and a few quick whacks with the iron is all I need to get it back if that happens. But in general, it stays put. That's what it's all about for me. Plus I can go from wet hair to out the door in waaaaay less time--I used to spend an hour and a half with that, now it's like 20 minutes blow drying and flat ironing combined, and it lasts for days. Maybe I'll iron 2-3 minutes on morning when I don't shampoo.
I was worried about it being too straight like it was the first time I got a Brazilian Blowout, but that hasn't been a problem. I can control the degree of straightness with styling. Sometimes I even wear it curly, or straighten just the bangs. This is fantastic stuff. Strongly recommend.