I am not currently using it, but my stylist used Nioxin on my hair for years. It worked fine for me. My hair did not seem as thin when I was using it. She explained Nioxin as a milder version of Rogaine. She said that unlike Rogaine, when one stops using Nioxin the hair will not fall out. I never tried Rogaine and do not know anyone who tried it, so this is all based on my old stylist.
I do not have thinning hair, but just thin hair in general.