I bought this as an upgrade to my first ecig, which was a Kangertech EVOD mega. The improvement in taste and flavour is stark, the K4 produces great clouds and allows you to really savour and enjoy your favourite e liquids. A fully charged battery will last you about 1.75 full tanks which is adequate but not outstanding. The K4 will use juice much quicker than more basic models like the EVOD mega, that's the trade off for the outstanding taste it delivers. Very easy to use, my only real criticism of the K4 is that it leaks out the airholes regularly. This can be avoided by reassembling and tightening the coil and tank with every refill, but that's a bit sticky and tedious to do each time. Hence the four stars rather than five.