Both my nicotine and concentrates arrived yesterday, which was a nice surprise. When I opened the concentrates to smell them I thought the JF Espresso Super Concentrate smelled more like a tobacco. That seems confirmed after mixing up a 10ml batch tonight (at the moment the smallest I can do without more accurate tools). I'm sure it's a tobacco flavour and not coffee. It's a very nice tobacco flavour, but I can't see how any amount of steeping will turn it into coffee. I don't know if there was an error when portioning it out because there's nothing in the description or the reviews that suggests it should be anything other than coffee.
However I did learn that mixing is not hard to do, and quite satisfying, and I can imagine that it will be a lot of fun when I start putting flavours together. Hopefully I'll be able to keep up the motivation through winter (when I tend to get a little depressed), or mix up enough to last through.