Just chiming in with my 2 cents... which is about what it's worth, LOL. I am a big clinical evidence type of person, but also of the mindset that anything that "can't hurt, might help" is worth trying for things like PPD, which are pretty darned serious. I think without loads of double-blind studies and whatnot, which we don't yet have, it's likely that the positive effect many see is some combination of the following:
-Actual hormones/etc. in the placenta that help
-Placebo effect (not BS! an actual cool effect that shouldn't be discounted!)
-A correlation between the birth experiences of women when they also end up encapsulating/eating the placenta vs. when they don't. I.e., I hear of many women who had mediocre to traumatic birth experiences, and then suffered PPD-- whether demonstrably "because" of those experiences or not. Then, these same women, often(-enough) tell of having no PPD with a later pregnancy where they ate their placentas... but that pregnancy also happened to be (usually) more empowered and ended with a more "natural" birth, (usually more peaceful/empowered) homebirth, birth center birth, VBAC, etc. Obviously this would frequently be the case, as if you even think to eat your placenta and are "allowed" to do so, you probably are planning/having a fairly empowered-type, natural birth. So-- correlation vs. causation, maybe. Not that this is always the case, of course, but I do see that running theme in general, so it's kind of hard to separate out the one variable, and that's aside from the possible/probably placebo effect that also exists even if the hormone/etc. theory is also true.
So! That said! I figure, "can't hurt, might help (and doesn't gross me out, so what the heck)." I am of the mindset that if it does have anything to do with hormones in the placenta and whatnot, it makes more biochemical sense to me that raw would be a better delivery method than cooked/encapsulated. I am also generally skeptical (not completely disbelieving, but skeptical) of TCM. So, to that end (and it doesn't hurt that it's cheaper), I will probably be cutting it up into small pieces, freezing it, and taking it as "pills" for a while. Especially since-- though this pregnancy itself has been amazingly free of mood swings-- I'm very prone to both depression and anxiety.