Been using mine for a few days now and I have to say I'm really loving it. Really solid little device. Battery life seems to be better than my IPV Mini II with the same batteries, but that is of course dependent on many variables. I've mainly been using it for temp control, so I'll have to try some similar kanthal builds across devices to reach a final verdict on that.
The temp control works fantastically, I like it better than my eVic VT in that regard due to a sort of work around that's possible on this mod that isn't on the eVic. On many nickle builds, I'll find that I need to start bumping the temperature up higher and higher for the same flavor and vapor production, around 100 degrees F higher, based on a baseline of dry hits occuring above around 420 degrees. On my eVic this is the only solution when this problem occurs, but I've found a better way with the D2. If I have a build that isn't being sensed accurately, I'll simply fire it at the higher setting, wait a couple of seconds, and lock in the now slightly higher resistance. This allows me to bring the temperature setting way down and away from the device's max to allow head room. I know this problem probably has more to do with my builds (though I can't see why, my wraps are always spaced evenly and close to or above 0.1) but being able to "glitch" the device back into an accurate AND consistent temperature curve is welcome to me. I wish I could test coil temperature while firing to have some data on this, but I don't have the equipment.
All in all I'm very happy with this mod, it does everything I want it to do and more in a solid small package for an unbeatable price. My main two nickle tanks (black subtank mini and goblin mini) look fantastic on it, and everything just works well. Highly recommended!