I think more clinical studies may be needed. I looked it up and it appears that it's a supplement not backed by the FDA.
One thing I find purely ironic is how many people complain about "big pharma" and chose natural products for everything when they don't realize (or refuse to realize) that the vast majority of it all is an elaborate scam. I'm mainly talking about all the magic "fat burning" supplements that Oz and others push out. I actually watched one of his 5 minute internet add things about a supplement that he said makes you not hungry. He had 2 women go on it for 3 days. One lady lost 3 lbs, the other lost 5 lbs and he said both had amazing results. Seriously, what medical professional wouldn't see loosing 5 lbs in 3 days as unhealthy when they claim all they've done was take the supplement but made no conscious effort to change lifestyle habits? Who knows, maybe these women had edema and lost all water weight or something.
As far as Amberen goes, it may be beneficial. I haven't done extensive research into it but as I said, I did notice it wasn't FDA backed and my initial suspicion is that it's a scam to appeal to healthcare hippies (people who think pharmaceuticals are evil profit makers and herbs/supplements are magic healers).