It might not be banned in the whole world. Also, there are a huge number of very strong stimulant compounds floating around. A lot of them are related to MDPV, a lot of them also are not.
Personally, I never had any real problems with MDPV. I got a bit too spun out a few times, but that is par for the course with stims. My come downs on it were
smoother then coke or amps to be honest. Biggest thing was it really upset my stomach and I'd puke my intestines up sometimes. It does seem to last FOREVER though. Esp with repeated dosing. Do not binge too heavy on it if your not use to strong stims or prone to mania or psychosis. (Actually, avoid it period if you are)
Contrast. My EX GF had some brutal come downs from it... almost suicidal like. (But again from being up and doing a cocktail of drugs for 5 days...) your milage may vary, be careful, start in small doses and do not repeat dose at first and unless you know what you getting into.