To what I know, a BT is basically transferring your balance from one CC to another. Which is why some cards offer you a 0% on balance transfers for X amount of time. It's an incentive for you to open a card with them because it is most likely the case that you are paying interest on a card you already have.
The advantage is that you have 0% interest for the time the CC offers you. also, if you have high util then by opening another card will lower your util.
The disadvantage is that you will add an INQ for applying for another card. Another thing you might find yourself doing is putting off paying the card because you know you have 0% for certain time.
I would recommend BT if you have a high interest rate and you are going to save money by BT. keep in mind, your goal should be to eventually pay that balance down to $0 or to keep your util to about 9-10%