I have been using my 7′s for almost two years. I absolutely love it and have been smoke free since then. In fact, I don’t even like the smell of cigarettes anymore and don’t like being around them. I have tried all the methods with my 7′s. At first I used the pre-loaded filters and even tried and liked the many flavors. I then used the refills for a long time. I really loved the flavor of them but they became messy and hard to travel with. I now use the cartomizers. They are very convenient and easy to use. I don’t like the flavor as much as the refills, but the convenience is worth it. Using the cartomizers also increases my battery life. When I used the refills, I was replacing the battery several times a day. Now I can use the same battery almost all day.