I don't know that we have very good statistics here on how many folks have quit altogether - I have seen a number of posts, but I would imagine that people who have quit don't have much reason to hang out here anymore. I see a lot of posts by people who use 0-nicotine juice pretty regularly, though. The amazing statistic to me, according to polls here, is the percentage of people who have been able to quit smoking cigarettes - 80% or better.
If you're curious about it, do some reading here and give it a shot. I was amazed at how easy it was to quit cigarettes, relative to attempts in the past. I smoked for over 40 years - I tried half-heartedly to quit a few times, and did quit for a year about 12 years back, but all it took was one cigarette to get me started again. While on vacation in October, a friend showed me his electronic cigar - I was intrigued by it, so I started doing some research when we got home, and stumbled onto this place. I wound up ordering a Vapor King from Vapor4Life - I wasn't hell-bent on quitting, but thought I'd try one out. The first 3 days I had 4-5 cigs a day (normally smoked a pack a day) - I had a few cravings that the e-cig didn't quite satisfy. I bumped up my nicotine level a bit to 24mg, and on the 4th day I didn't have any cigarettes, and haven't had one since. I still have 3 and a half packs of Marlboros sitting around gathering dust, but have not been tempted to light one - I can't begin to imagine me not caving in under any other circumstances. I've had a few odd mild cravings from time to time, but I am fairly certain they have nothing to do with nicotine. I have started to reduce my nicotine levels in the past few days with no problem - maybe I'll get to 0 someday. Even if I don't get to 0, I am happy to have my sense of smell and taste back, and not smell like an ashtray. Give it a try!