I love this product but found that I needed to upgrade the battery within in the first 2 months. This is a great way to quit smoking. I was smoking two packs a day and just put them down when I starting using this product. This product can be used if you smoke a little or a lot. It is easy to control Effectiveness This is a very effective way to quit cigarettes. Ease of Use It is very easy use once you figure out how the coil works and to change it. The coil last 2 weeks but depends on how much you use it. Side Effects I did not have any side effects using this product. The trick to that is the amount of nicotine that you use in the e liquid. Immediacy When you are feeling like having a cigarette this is a great way to keep that craving under control. Dosage Control The dosage depends on the amount of nicotine in the e-liquid and how many times you draw on the e-cigarette. There have been days when I needed more than others but it just depends on me on how quick I want to withdraw from the nicotine.