It was touch and go a couple years ago. Some people were getting their stuff confiscated in confusion over a ban on imports of e-cigs, and whether or not it applied to personal use of tourists. That ban on imports has since been lifted, and so there should be no more confusion at the border regarding tourists bringing in their own for personal use. As someone else mentioned, it MUST be in your carry on, not in checked luggage. Also, make sure your liquids are in containers of 180ml or less (3oz) and in a closed baggie. You should be good to go.