Very Easy to use pen with simple disposals cartridges, drawbacks would be the length of time cartridges and the battery last, I am a regular smoker and cartridges will last between 1 to 3 days and the battery between 1 and 2. However, a good substitute for cigarettes with nice flavours and a variety of nicotine strength cartridges. 18mg is a good hit but I've lowered to 6mg. The product is also a good small size and has a good simple and stylish look. Other substitute smoking products are more economical in the long run as you receive a higher amount of liquid to consume, but I personally am happy to regularly purchase cartridges for the simplicity and easiness of using the product for the moment.