I experienced insomnia while using Maca, as well as a couple other unwanted psychological effects like hyperactivity and inability to focus. I actually felt really dumb while using it; however, I did notice a probable libido increase. It made my feet very cold though, which suggests that it works on thyroid (some research supports this). All in all, it was a supplement that caused good and bad things for me, so I discontinued it.
If you're looking for a libido boost, I highly suggest trying fresh-squeezed pomegranate juice.