I have one. I am still on my first coil they have great longevity. The 1.6 coil has a break in period of about 8 ml but then the flavor gets good. The 0.8 coil is supposed to be good right out of the gate, but I haven't tried it yet still waiting for my first coil to die. I've put at least 20-24 ml through it still going strong.
Overall, it's a nice well-designed tank that is well put together, easy to use, and has 4 ml capacity. I didn't enjoy my first 8 ml or so (I should have used storebought, I think) but after that I just consider it a well made, useful and interesting topfill tank. It doesn't leak, I don't consider that it's better than some of my other MTL tanks, but it is nice, well designed and etc. I guess the topfill and capacity are one of the nicer things about it. It's also nice the coils last as they aren't cheap. If you are wondering about it ,well to me it has more positives than negatives, and it's a tank I like to use....
Anna