David Pearce puts things better, in my view:

"Worse, the psychedelics aren't primarily euphoriants. They don’t directly stimulate the pleasure-centres and guarantee the user a good trip. Both the serotonin- and catecholamine-like families trigger psychedelia mainly via their role as partial agonists of the 5-HT2A receptors in the central nervous system; 5-HT2 heteroreceptors exert a tonic inhibitory effect on the striatal dopaminergic neurons. Such agents aren’t a dependable choice of clinical or recreational mood-brightener, whether in the short- or long-term."

• http://www.biopsychiatry.com/