Your friend's experiences are not uncommon. Psychedelic drug use is commonly associated with a heightened sense of well being in the after math. There have been some studies done on psylocybin showing people are happier during/after its use:

http://www.csp.org/psilocybin/Hopkins-CSP-Psilocybin2006.pdf

I don't have too many opinions on the subject. I generally default to a desire for further and in detailed study on any compound with the potential for benefits to people, drug or non drug.