I smoked it for a couple of years (K2, 777, Mr. Nice Guy) & the compounds that attach to the cannabanoid receptors in the brain are proprietary & here in the US, whenever a specific compound is banned by a local or state gov't the companies simply create a new compound to legally get around the bans...& since they (the compounds) are treated as proprietary, there's no legal way to insure consistency & safety.
Before I tried it for the first time, I did my research & I understood alot of the risks & went in eyes open. It was an ok substitute for real weed. the high was kinda similar...different, much stronger, but similar enough. It was even kinda fun sometimes, but overall, the problems overshadowed the positive.
One of the worst things was overdosing...even a little bit. In my case, if I took one hit too many, it would scare me (not classic paranoia, but a feeling of fear that made me think it could make me stroke out or force my liver to fail...so like an idiot, I made more of an effort not to oversmoke it. ...before I knew it, I came to figure out THE worst thing about it.
About a year or so ago, For a week & a half I had what I thought was the worst case of the flu ever, but after I recovered, I came to figure out I went through physical withdrawal.
I'm not the kind of guy to tell people not to do drugs, so I won't tell anyone not to do this drug, all I'll say is that I did this drug & I deeply regret it.