I tried it for a few months and found it to be a really good experience. I met people who I would typically not meet. I could go on several dates per week and often they were very original, different and creative first dates.
However, in the run long I was not able to find success dating online. I found that there was often a lack of chemistry - despite having many things in common (having been "matched").
For me, when someone asks you out in person, there's already some kind of connection. You chit chat for a bit and when you go on your first date you can recall moments from your first meeting that create conversation. Online dating was like going in cold for me. Despite knowing that you had so many things in common it was your first time meeting and a bit awkward.
In the end I quit online dating and met my boyfriend (he's pretty awesome) in a Safeway of all places. I guess romance can be found even in the pasta aisle...