There's precedent that says it can work with very few side-effects -- coffee, basically, coffee is my whole justification, and I guess to a lesser extent nicotene (now that we can deliver it without carcinogens, at least as far as current research would indicate). There's precedent that says it can totally destroy you -- mescaline, shrooms, crack, take your destructive pick. The long and short of it is, very few chemical compounds are created equal, and biological processes are somewhat chaotic. Heck, we can't even all eat the same foods, on account of allergic reactions. I imagine some people will respond positively to some such drugs, depending on the drug, while others might be destroyed by it. So, speculation -- on a chemical level -- is pretty much a moot point.

Ethically speaking..... well that's up to each of us, isn't it? Responsible use could give -- not just our society, not just our species, but our whole [i]planet[/i] could reap enormous benefits from something like this. Selfish or reckless use could ruin the world, or worse, your life. I don't think that's necessarily a reason to throw in the towel, and say "Screw it, we just won't look into this, it could turn into a monster movie," but obviously discovery is a perilous endeavor, and we should all operate with an understanding that certain knowledge, like the atom bomb, can be dangerous.