I have met 4 people who are on this site, and both times were good. Well to be honest, 2 i visit in the states quite often. To me its a good holiday plus I am being able to talk in person people I consider good friends.
The first time I flew to the states I was scared, I think it was more what they would make of me than what if they don't meet up to my expectations. I think this stems from the fact that I used to connect toa few bulletin boards before the net really took off over here, and went to a few meets. They were good times and made some good friends.
If you are going to meet someone for the first time, just don't get your expectations of the person you are going to meet too high. Then when you actually do meet and they are better in person than online, then you will better for actually going through with it.
