I could not be more enthusiastic about this tank. It is simply a brilliant design. Filling it is easy and no mess. Just take the dropper or unicorn bottle and apply small pressure to the spring loaded mechanism in the drip cap and it opens and you can fill. The mechanism is easy to open with downward pressure, but prevents leakage from the inside out. Replacing the coil is similarly easy. Simply unscrew the top chamber, slide the old coil up off the filling tube, slide the new one back over it and replace the top chamber. Priming it is as simple as filling the tank and inverting it for two minutes. The top air flow is also a fantastic feature as my previous tank had issues with leakage from the coil into the bottom airflow. Gravity alone minimises the risk with this model, as well as the rest of the design. The protective cap is a really nice touch. I constantly had issues picking up bits and pieces in the mouthpiece of my old tank when in my pocket or under the dashboard in the car. I slid the ring for mine down a bit further than is pictured here to provide some impact resistance for the glass. The unit gives a better and cleaner hit than my old unit at 80 watts with the same wattage and has slightly lower resistance. It pairs up well with my mod which is a Vaporesso Armour Pro that supports up to 100 watts. Couldn't be happier. No leaking at all, great vaping, great value for money, beautifully presented and packaged and nice little extra's like the protective cap. If I tried really hard to find a negative it would be that I will probably need to spend more on vape juice because it's much more enjoyable.