I loved using eHarmony -- and had no privacy issues. In fact, I really enjoyed that the first portion of the communication is relatively anonymous, except of course that they can see your photo! You start off with basic, not-too-intimate questions that sort the wheat from the chaff (basic values stuff, must-have's and can't stands) and then when you're ready you move into more revealing communication, and then when you're ready you can move to email and then phone. You can take as much or as little time as you like in each stage, and at any point you can hit the button that sends them down the garbage chute. Err, I mean, you can pass on someone respectfully and without any muss or fuss. It can sting a little when you're communicating with someone and you get a message that says they're "closing" you because they realize you're not compatible, or worse, that "no reason is given." But still, that's easier than getting "closed" in real world dating when someone just stops returning your calls.
It's a risk either way, getting to know someone's insides before you meet their body, or getting to know their outsides before you get to know their insides. You might really fall in love with someone's insides and then find out when you meet them that there's no real world chemistry. And you might fall in love with someone's outsides and then find out they are a Kenny G fan.
Either way, it's fun, it's an adventure, it's a growing experience.