I have met a number of girls through online personal sites and have had a number of differing experiences. I've talked with one girl for almost a year and we never did end up meeting in person or even talking over the phone. I've met another girl who I had talked to for a day or two over IM, and had a very bad first date. But on the other side of the spectrum, I recently went out on the first date with a girl who I had only talked to on the phone that afternoon to setup a date. We really hit it off that night and last night we agreed to make the relationship exclusive, so I won't need my profiles on the personals websites any longer. It's a very good feeling when it all works out and you find the right person! Basically, you have to decide if you are comfortable. The more you date people you initially meet online, the more comfortable you become with it.
Good luck and remember to be patient but persistent!