I'm from Russia and I can relate, alpha-PVP is far more worse problem, because it's 2x cheaper and 3x potent, and causes the psychosis easily, mephedrone is one of the safest stimulant type drug. I've binged a tons of it and almost never had problems. Mepthedrone killed mostly all drugs in the market. Meth, Amp, Coke, E, MDMA... all got deprecated. So now we only have Meph, Alpha, Methadone, and hash and I can say it's pretty "healthy" market if we exclude Alpha. Far more healthier than what we had in early 90s before dark web.
I've tried Meth and MDMA and coke, they all far worse in effects and especially side effects. The only problem is that mephedrone gets very addictive especially first times. And I saw some of my friends starts to IV it (me either). This route is very bad for itself, after first times you got much stronger addiction and doses increases a lot. Typical one time dose for me was 350mg IV. However recovery from mephedrone is ultra fast and never got long term effects like MDMA.