Hi there. I don't have any experience with this product, but I did a little research for you.
This site has a good description of the process.
About Pravana products
It doesn't actually seem to be a true keratin straightener. It seems more like a mild relaxer. The active ingredient is cysteamine. Reading the description of the process, it sounds like it works on the same principle as the Jheri curl.
They have a demi-permanent option. If you are really nervous about it, you could do sort of a test run, and see if you like the results before going permanent. Also, you should consider the cost. Presumably, you're going to have to get touch-ups on your new growth.
This is a stylist's opinion:
TR Forum - Pravana Keratin Fusion
I found one thread about this product (the demi-perm, I think) on NC. The poster seemed very happy with her results.
Pravana keratin fusion treatment