^^Good article.
Mephedrone is without a doubt dangerous stuff, there's simply nothing known about its impact on the human organism and long term side effects.
However I think people should be careful about pointing the finger of blame solely at mephedrone for recent deaths...these people all seem to have mixed substances, with possibly very dangerous reactions, and some of which for all we know, could be creating new, unknown toxic byproducts (like the reaction of cocaine and alcohol together forming even nastier cocoaethylene), and people have died also seem to fiend it in massive doses or over a long time.
I've used it a few times, and won't be doing so again. We are all individuals and react differently to things, but I personally found the buzz very social, chatty and warm, if short lived, and I tended to sober up once the effects wore off...nothing like the feeling of coming down from an ecstasy/MDMA high...I HATE that empty feeling, and a few hours of fun is not worth that feeling for me anymore. On the 'fiending it' front...I agree and disagree. When I started to use it, there would be temptation to redose, after a few times, myself and friends learned not to, it didn't enhance the experience at all, and I would simply not be interested in doing so, even when offered it freely.
It won't be the end of the 'legal highs' saga however...some other legal and possibly nastier chemicals like MDPV are ready to fill the void (much more potent, much longer lasting, more addictive, with serious long-term side effects hangover effects compared to mephedrone). There is some other chemical labs in China have started to produce apparently even nastier naphyrone...may be very much more dangerous, with a serious chance of neurotoxicity brain damage. Brings to mind thoughts of 'drug terrorism' in a sense, for anyone who has read/seen 'A Scanner Darkly'.