I have had my Evic for about 6 weeks now and I am very impressed with not only the performance of the device but what you can do with it. The battery life is beyond excellent and the control top notch. You can tap into the online software and update and track your usage statistics and update the firmware.
I love to tinker and research and analyze so with the LED screen you can fine tune the different juices and even fine tune the hit and vapor as your tank levels change. I have used it with top and bottom coil tanks and find each performs equally well yet differently (hence the tuning of the VV/VW). This is especially nice if you change the coils with different OHMS. Here's a link to a helpful chart for general settings:
Helpful Chart For Pairing Atomizer Resistance To Battery Volts - Help It Broke! - Technical Issues - Vapor Talk E Cig Forum
I have not had one problem or glitch. I encourage you to visit the website and you tube reviews and Google Evic for more info. I don't think you will be disappointed in this VV/VW device in IMHO