You decide what is a Pro and what is a Con. "One person's junk is another person's treasure."--I'm sure this person was talking about objects/possessions, but the same principle can apply.
Pros:
One advantage of online dating is that you do not have to get ready (dressed, grooming,...) for an actual date, unless you are using a webcam, smart phone or other device that involves real time video. This may be a "con" for you if you enjoy getting "dressed up."
You don't have to leave your house/apartment to get a date!
You don't have to wait until you meet someone in a bar, grocery store, or one of the other places "the magazines" tell us where to meet someone. You just go online.
Online dating reduces the odds of being humiliated! If you don't like someone or s/he doesn't like you--no loss.
You get to "know" a person in a short time period. Some people love to chat anonymously without "being judged." This may be a "con" if the person is not being truthful.
You do not need to reveal your name, address and other personal information as you probably would on a physical date.
Cons:
You don’t know who is really behind a profile. Use caution! Anybody can cut-and-paste a photo of another person off the Internet. The anonymity that protects you, unfortunately, may protect some unscrupulous person who is just clowning around or might intend harm. On some free sites, some may sign up just to check out profiles/photos, while others may be collecting e-mail addresses and other info with the intentions of perpetrating some type of scam.
Some members may misrepresent themselves in their: appearance, financial status, marital status, age and/or gender. You may be doing this to protect yourself--but remember--it can work both ways.
You don't have physical contact. This may come later, if this is what you desire. This may be a "pro" for you if you are just looking for a "distant" relationship.
Some dating sites are free, while others charge a fee. Pay sites offer more features, as you might suspect. This ($) can add up over time.
_____