I have both the black and the stainless versions of the ePower 14650s. I've not had ANY problems at all with the finish on any part of them, nor have I had any issues with threading.
Both came with the newer switches (the harder plastic vs the soft rubber) and on the black one, I have noticed a little silliness where it will stay on after I've released it, and has to be wiggled a bit.
Also, I've read that the ePower was supposed to be regulated so that the last hit before the battery is drained is supposed to be as good as the first. However, what I've noticed is that after a while, I seem to get less vapor and flavor. If I drop a fresh battery in it, all is well. Not a HUGE complaint, being that the battery still lasts a good while, but it's not what was 'advertised'. Mind you, I don't have a meter to be able to confirm.
Other than that, they've been pretty decent devices.