What have been your personal experiences with Crystal methamphetamine?

I don't take any drugs myself, but I am very close with people who do. I believe that drugs, Crystal in particular, can change a person very much. I'd like to know what other people's experiences have been, whether you've taken it or known someone who has taken it.

Please no comments about how bad drugs are. That's obvious.

Thanks :D

: http://alcoholdrugstreatment.info/what-have-been-your-personal-experiences-with-crystal-methamphetamine