I went on them in my early twenties due to a nervous breakdown, and while they stopped the endless loops of thought and insomnia (I ended up sleeping ten hours a night without breaking a sweat), they reduced my libido, made me gain weight, and worst of all, robbed me of my natural sharpness and creativity. It was as if my brain had been wrapped in a layer of bubble wrap, and my ability to come up with those sparks of inspiration that you need to do intellectual work was almost extinguished. I'm 100% now, fully recovered, but it took me about 3-4 years to get back where I was before it all happened. If your doctor thinks you're right for them, go for it, but only as a last resort.
They do work, but they're the last tool in the box that you only want to use when everything else has failed.