I got the Brazilian Blowout before and blogged about it. =) It seems that it's safe enough for those who want to get the procedure done as opposed to the stylists that are implementing it all the time. Here are my blogs if you want to read up on what I thought and of its results! I also compare it to the Japanese magic straightening process if you want to read about it here. 

I've had the Brazilliam Keratin. I haven't experienced any adverse effect from it, but I've only had it once. Just as the above poster mentioned, the controversy was surrounding stylist's being exposed to it on a daily basis because of a chemical called formaldehyde. Overexposure can be harmful to your health. At most salons, they've discontinued use of keratin treatments containing formaldehyde. But for your peace of mind you can always double check with the salon before you visit!