Wow! $15? What a score! I'd love to read your comments.
Sorry it's taken me a while to get around to this. For one thing, I wanted to give all the coils a shot and I've also been pretty busy lately. However, I'm here now, about two weeks into my D1...and it's AWESOME!!! Having owned a Crown 1 since two or three weeks after it came out and two Crown 2s (I never got a Rafale, but from all that I've read it doesn't stand up to the Crowns, assuming the coils are quality), I've had a fair amount of experience with Uwell tanks. The D1 is their best tank to date, bar none. It has better flavor than the Crown 1, which has better flavor than the Crown 2, IMHO. The coils last longer than either of the other tanks for the most part, although I've had one that crapped out pretty quickly (but I used some darker juices with it so...it could've been the juices that gunked it up and killed the flavor early). The unique design works extremely well with regard to leaking, as in there hasn't been a drop of it yet. There has been some juice that has collected in the bottom compartment meant for condensation collection, but it hasn't spilled on me once (except one time when I wasn't paying attention and turned the tank upside down with the cap off, so I can hardly blame Uwell for that).
As far as I can tell, there's only one minor downside to the tank, and that's its somewhat restrictive airflow. I usually find myself taking an entire lungfull on each draw rather than pulling about half a lungfull of vapor and following it with half of one with air like I do with most tanks. That said, I usually stick to the lower end of the recommended wattage for each coil. As a test, I just cranked the 0.5-ohm coil up to it's recommended max of 60 watts and it does make for a thicker vape without getting too hot, so I may have to use these in the upper end of the power spectrum more often. I'm afraid that using them at higher wattages will burn out the coils more quickly, but I'll try it out and see if I can tell a difference.
Just as a comparison, I have (purchased in this order) an Atlantis, Triton 2, TFV4, Crown 1, two Cleitos, a Horizon Arctic V8 Mini, two Crown 2s, and a TFV8 Baby Beast. I've also got a ton of ProTanks and other MTL tanks, but I haven't used them in years.
I do question the stated 4ml capacity. It seems like it holds closer to 3ml. That doesn't bother me, though, because I like to change flavors frequently.
All in all, I love the thing. It's my new #1 tank. If you're in the market for a solidly built sub-ohm tank that has RDA flavor and won't dump half your juice out on your hand or table, grab a D1 from Ecig. I think they've upped the price by a dollar or two, but it's still extremely reasonable.