There are a few pitfalls. The first is that some people doing free internet dating aren’t really looking for a relationship and you don’t always know that based on their profile. You’ll have to weed those people out. Also, some of the free sites don’t offer much in the way of a usable design or a quality search function because they’re free and they presumably have less of a budget for those types of things. They probably also assume that people doing free internet dating aren’t going to complain too much when the site isn’t perfect.
Free internet dating allows you to explore and connect with people without making a financial commitment. Some of the big sites charge a ridiculous amount of money for their services that seems particularly criminal when you can just use a free site for nothing. The high volume of users means that you can almost certainly find what you’re looking for in any given city and since everyone is there to meet people at the very least you don’t have to be afraid to just put yourself out there and start asking people to chat or meet. Free internet dating has almost everything the pay sites have so give it a try.