I subscribed pretty early, and I've been happy with them. When I started vaping, I used to buy samples every week, looking for new and interesting flavors. Picking vendors, PG/VG ratios, and flavors, and keeping track of what I liked and needed to buy more of, plus looking for new places to buy e-liquid started to get like work.
ZB makes it a whole lot easier for me. I've found quite a few favorites and must-haves because of them.
The thing is i get different flavor profiles, i put that i wanted fruit and i got dessert and food flavors...put 3 nic but got 6 on almost all of them
I've never done that profile thing because I don't want to limit my samples, but as to nicotine, if I understand correctly, if your selected level isn't available, they'll send you the closest they have from that vendor.