I have been using this for a few days and it is fantastic. The only thing that needs improvement is that there is a very tiny plug for the fill hole in the tank/vaporizer units that must be carefully removed and replaced with tweezers. The tank / vaporizer units hold about 2 ml. The battery has the 5-click on-off feature but the 5 clicks must be done rapidly, then the blue light will blink 3X to confirm on or off mode. It comes with a fill bottle with a small fill tube. The flow is slow so it takes maybe a minute to fill with a hard squeeze [be sure cap is on tight !]. This fill cap fits my 5, 10 and 30 ml bottles. Battery time is just not an issue, I have used one all day and it only required about 30 minutes to re-charge. I will keep my white "cigarette" style units for times when I want something more normal looking, but their problems of low battery time and cartomizer capacity are OVER !!! The EGO W draws as easy as an analog and with as much "smoke".