Used neos on and off for much of this year, before devloping a pronounced aversion to them: threw up after 2 SPirits on a lot of red wine, and got the taste caught in my throat for hours. I used once more after that - 5 mixed spirits/doves - and went on a twelve-hour compulsive soft porn marathon that wasn't characteristic at all (generally don't like porn.) I'd binged on up to 11 per session, and initially thought they were some kind of bk-mbdb or related chem.
Over time, in part from talking to Israelis, I realised they were cathinone-derived, or some kind of precursor chem too obscure to be illegal. I've seen friends get into real trouble with them, chomping 20 or more in a week of habitual use: which, given the ridiculousy addictive profile of methcathinone (cat), leaves me strognly suspecting they're a second-order meth- or eth-cathinone derivative or precursor of some kind.
Some blends - SCs = are just stimulating, and so not to my current taste (too much speed in college: heebiejeebies on anything too upbeat now, more of an MDXX fan), but those is particular seem to be at least as addictive as coke, arguably more some.
Conclusion: a loophole-legal khat-derived cat analogue, that's much more dangerous than pure MDXX, and as habit-forming as meth. A lot of people have been burned by them, and some are having trouble quitting. After my early enthusiasm I'd say stay the hell away. There's equally potent - and much safer - legal (in most of Europe, anyway), pills on the market, if you know where to look.