Shot of my two primary go-to devices (eVic-S included) and tanks.

PBusardo has posted his extensive e-Vic Supreme review.
Taste Your Juice | THE EVIC SUPREMELY LONG REVIEW
His review reflects pretty much my my peeves but in great detail. Spoiler alert - first review where he concludes no overall thumbs up/down. This two part 90 minute marathon will become a PBusardo classic review. The man is a review machine. JoyTech should be paying him for his engineering and ergonomic feedback, as all of his advice is very detailed and well thought out. It surprises me that the JoyTech engineers didn't pick these things up.
Even with all the shortcomings, I still give this device a hearty thumbs up. I expect JoyTech will be pouring over his review and fixing what they can in a Firmware upgrade (a powerful advantage of this platform). Some of the thumbs down Phil gave are really minor in IMHO.
Given that the 510 connection is removable, there is the possibility of Joytech releasing a new 510 connection that eliminates the gap with some toppers/topcaps. The sharpness of the endcap could also be addressed with a new endcap. So most of the physical issues are addressable in a post release firmware and device upgrades. Can't say that for many devices out there.
My advice to JoyTech is this - debug your e-Vic S firmware and do a second gen device that is formatted more like the ZNA. Don't copy the ZNA but what suprises me is that nobody has picked up Zen's fundamental design around reducing mod height with a side-slip style of their own. Those of us who are not box-mod fans would love a device where the control head parallels the battery compartment. I think JoyTech has a really good control package, surrounded by a mediocre tube design. Much like my retired iTaste 134 original, the length of this device is a really challenge for pocket portability - this is not a take to work device IMHO. I did see a VaporShark DNA30 box mod yesterday in person and I have kinda warmed up to the ergonomic advantages of that particular device. Now if you had an e-Vic S control head in a tube-mod style, parallel with the battery, but not in box form, I think it would be a great alternative to those trying to score a ZNA.