I too got keratin treatment done twice so far. I think I am going for another pretty soon. The results are definitely amazing, shine, manageability...lots of compliments.
However, the results are not the same for every type of hair. Some do not achieve the expected results for specific reasons...inexperienced hairdresser, self-neglect, etc. It does require a little TLC afterwards to continue the results...sulfate-free hair products, etc.
I have yet to try the OTC version...little skeptical.
If you are really considering getting keratin treatment done, go for it. The results will leave you impressed.