I've been on Saw Palmetto for about 6 months, though I do combine it with a healthier diet, a multivitamin as well as Fish Oil and SIlica tablets daily. While I can't say that the SP has actually shown any regrowth, it certainly has not slowed anything down nor caused any shedding. Furthermore, I have never experienced the sides a lot of peeps mention here (ie: man boobs, decreased libido, pain in the jewels, etc.) in fact, I feel like it has increased my sex drive to a certain degree. I suppose the universal law applies with all of this, in that all things work differently for different people.
I also firmly believe that just because a treatment - be it all natural or not - is not FDA approved, doesn't mean it should be dismissed. There may be a lot of trial and error involved and may take a longer time to see results, but I do think a healthy diet and alleviating any stress (not always easy these days but it's worth an effort) is the first building block. After that, there are numerous things you can get from the health food store and try at home, and with a lot of patience and a positive outlook, you might be surprised.
Aloe vera, apple cider vinegar, coconut oil, ginseng, ginger, sea kelp, onion and garlic, saw palmetto, licorice, lavender, rosemary, etc., I think all of these, in whatever proportions and combination (and that may be the key) can be very effective in not only stopping the hair loss, but also to obtain regrowth.
I will never diss Rogaine and all the others, and I'm holding out on using the foam (been thinking about adding it just to see if it speeds things up), but combining pharma stuff with natural remedies, scalp massaging and a healthier diet can be the best of all worlds.
So again in regards to saw palmetto, for me, not an ecstatic oh-my-god YAY, but certainly not a NAY, it just takes time to see results, like with all the others.