I used eHarmony for a grand total of two days. Way too much hand-holding, though I suppose I didn't spend enough time on the site to let that work for me. There was practically no customization allowed; the profiles are completely canned.

Again, this might work really well for those that are serious about online dating, but for those that are not, it is hardly a justification of being out several dollars a month (which is collected lump sum at registration too). I got my refund pretty easily, though. Took one call to customer service and the explanation I just posted here.