Positives: it relaxes you quite a bit and helps you fall asleep calmly, of course not immediately after long hours of computer use or from overstimulation (argument) or staying up all night. You need to help the situation as well, it's not exactly a sleeping pill that will knock you out cold.
Negatives: it has a bad taste like drinking green grass juice (that's why I don't drink it straight) and sometimes you wake up abruptly from deep sleep (like with Melatonin pills) and then it's hard to fall back asleep, but until you get up completely, you are calm.
It has a better taste-smell in the room than Valerian and it doesn't upset my stomach like that one does.
I have also tried passionflower which you boil in a pot and then strain, etc., but apart from the time-consuming nature of it, it doesn't have any serious effect.
Tip: if you add a little water and then the drops, you will notice that after those they float, like oil in water, there is no separation, so I first add the drops and slowly pour the water on top, and the mixture is made immediately.