What are the long term negative effects of crystal meth use?

I know a few people who use meth on a regular basis. I've done it myself, and though I know its illegal, I don't know what the adverse effects could be from regular use. I think everything in moderation is ok, but is this an exception to that rule?

: http://alcoholdrugstreatment.info/what-are-the-long-term-negative-effects-of-crystal-meth-use