There's no tar or any of the other crap they put in cigs (and some smoking cessation products).
You have an enormous buffet of flavor and strength choices for your eLiquids. And once you find the liquid that becomes your ADV (All Day Vape), nothing is more satisfying after a meal or with your coffee/tea in the morning. For me, a few hits of Mystic Juice Babylon after a meal is a slice of heaven.
You'll save a nice chunk of change...a 10ml bottle of something I vape all day, everyday will last me about 1-1.5 weeks and costs around 5.00. I'm a former pack a day smoker, so I vape quite a bit.
Just beware of shinyitis and gadget mania. eCigs can be quite a fun and interesting hobby.
I really can't think of any downsides. Get a case or a lanyard to make taking it out with you easier. You'll be wanting to get replacement heads/coils for whatever you're using for your juice if it's not one of the disposable kinds that you throw out once washing it out is no longer working. But that's no great expense and is as easy as changing a lightbulb.