Multiple upload options: The battery is what keeps you going. If you choose an electronic cigarette kit that only has a USB charger, then you will be out of luck when you download and do not have near a computer to charge it.
Make sure you get an electronic cigarette kit that offers you multiple charging options - preferably a car adapter and a wall adapter. It is nice to have guarantees that you will be able to charge the battery wherever you are.
Taste: Let's face it, we can certainly smoke any cigarette we want, but the only ones you will enjoy are those with a great taste. You might want to change its flavor to match your mood or want to try a number of flavors until you find your favorite. The point is that while more flavor options, it is more likely that you will find the best taste for yourself.
Cartomizer Life: This is another "use" thing. Yes, you want to make sure you get a good taste, but you also want the taste to last. It's really annoying to have to change your cartomizer after 50 puffs - even if you paid a cheaper price for that cartomizer.