I like using one, it is just a small disk you slide into the tube. you have to open the tube to adjust the wattage but usually if you use the same atty all the time it isnt a big deal.
I have a kraken on a nemesis with a kick at about 12 watts.
the power stays consistant and unlike a standard mech i can get to about 3.2volts without the vapor dropping off, without the kick I would be recharging around 3.6v and by then the vapor is pretty week.
If you like to adjust your mod a lot it isnt really for that, it is more once you find the sweet spot your looking for you leave it alone, with minor adjustments if needed.