The advantage of being a swing voter in an election is that you have much more of a chance to decide the election. For example, in our current system, people in many states have very little chance to impact presidential elections. They live in states that are not “up for grabs” and therefore will not be likely to have much influence on who wins. Swing voters, by contrast, are much more influential. Their votes can help decide the election. The candidates craft their appeals to these voters, thus giving the voters more influence over what policies the candidates are espousing.
The major disadvantage is that you are more likely to be deluged with advertising. There will be a great deal of competition for your vote and so you will be targeted by many ads. There is also more pressure on a swing voter to decide “correctly.”