After reading Erowid for the past 5+ years, I know how cyclobenzaprine, mirtazapine, hydroxyzine, & gabapentin affects other people.
Yet, having been prescribed each of the above medication, I have also experienced their effect on me.
Gabapentin actually contributed to mood swings mid-December 2010 until mid-January. Sure, it did make me more talkative. When I was tapering down to zero I felt some of the withdrawal side effects (agitation, anxiety, dizziness, disorientation, headaches).
For a week at the beginning of February, I was prescribed a week's supply of cyclobenzaprine for muscle tension in my shoulder. It helped relieve muscle tension and pain, but a careful study of its use helped me to decide it was usefulness is limited.
In March 2011, the sedative effect of hydroxyzine was great for killing addiction for nicotine, and I'm grateful for that. I received this medication in April 2010 but stopped taking it in May 2010 when I was first prescribed mirtazapine.
As well, mirtazapine's strong sedative effect also helped me not want to use it anymore after tapering off it back in December 2010.
Currently I don't use medication. There are better alternatives to them such as talk therapy, meditation, and regular daily exercise.
However, I'm still open to use of medication as prescribed.