I'll go ahead and say what my experience with JWH-018 has been, but it hasn't been terribly eventful.
I got JWH-018 because it was about to be banned and I wanted to try it and it became cheap as hell right before the ban. So after getting it I really liked it, mainly because it was super cheap, didn't leave me burnt out once I came down, didn't make me tired (made me energetic actually) and was more psychedelic then weed. I also liked the fact that it left me much less disabled then weed would leave me.
So I began smoking the JWH-018 every day or almost every day. I also continued to smoke weed every day, I would usually smoke JWH on its own in the morning, and then in the mid or early afternoon I'd smoke weed with JWH, then at night I'd smoke weed on its own. Usually I smoked about 3-6 bowls a day. With joints and blunts liberally thrown in, of course.
I did this for about 2 months, and then one day I accidently smoked too much. I always eye out my doses, the reason I smoked too much is that I smoked one pile off tin foil, which I hadn't done much before and I thought I wasted it. So about 1 minute later I smoked another pile, and then 2 or 3 minutes after that both piles hit me hard.
It wasn't too bad, I actually liked the visuals that I got, which were very pronounced, both OEV and CEV. The problem was that I felt scared for no reason (kinda like I've felt on bad DOM trips, except DOM is way scarier). I was totally coherent and knew that I had just smoked too much JWH, but that didn't stop the fear and anxiety. I was also shaking violently for the duration of the trip, presumably due to GABA inhibition. It felt unpleasant in a similar way to salvia, and the visuals also reminded me of salvia.
So the fear, visuals, and tremors contiinued for about 30-45 minutes. Then I stopped feeling bad and was just insanely stoned feeling. Like I couldn't walk straight for another few hours. My eyes during this experience were more red then I had ever seen them, if that's worth mentioning.
Since then, I still smoke JWH-018. At first I kept doing it every day, but I prefer weed to JWH (always have), so now I smoke weed only most days, and JWH 1-4 days per week usually.