I've been a member of Chemistry.com for a long time. I was drawn to them because they used a matching system that was designed to bring people together for something longer term. I dont think they do as good a job with their matching as eHarmony. With that said, I dont get a whole lot of people who are way out of the ballpark as matches, so to speak. I do tend to get some matches who are farther than I should be getting - Im in St Louis, and I've gotten matches in Decatur, IL (130 miles away) and as far away as Chicago (300 miles); I specified a search radius of around 50 or 60 miles. These are rare though; maybe one every 3 months or so. Really, I like what the site tries to do, but it just doesnt work.
Another annoying feature is that if you like one of your matches and you click the "interested" button, it gives you the option to email them. But its a small little box - am I supposed to just write a few short lines, or do I write a full up email? If you choose not to write, you have to go to a separate screen where all your matches are (and its not always in chronological order), and you have the option to choose one of a few icebreakers. But most of the icebreakers are either stupid or I believe they are more likely to drive people apart.
Like other sites, there's a lot of dead profiles they match you up with and most people you show interest in dont respond. It does however show the last time the person was active.