I have a kamry K200, and it works OK. It was my first APV, and it did the job much better than the eGo-T's I was using before, but it doesn't vape as well as my Segelei ZMAX v2 or VAMO v5. I don't use it as my primary mod anymore, but I always have it as a backup mod. I primarily use it for ohm checking, and voltage/wattage tuning with a new coil or new juice (since it uses dedicated buttons for it's functions, it is much faster to check resistance or adjust output than most other mods that use a menu type system). That being said, for only $27 it is still a good mod. It is also very light since it's made from Aluminum.
As far as coil resistance goes; it will not fire with a sub-ohm coil on it. Generally speaking, no VV/VW mod will fire with a sub-ohm coil (with the exception of some older mods like the lavatube which [I have read] will fire with a sub-ohm coil, however they down volt themselves to stay within the power limit of the pcb, which defeats the purpose of using a sub-ohm coil in the first place). If you want to make .5ohm coils than you need to get a mechanical mod and some good quality high-drain IMR batteries for it (I use MNKE IMR-18650's which can handle 20A continuous draw (30A max), many people prefer AW and eFest IMRs.
Good Luck and Happy Vaping
