this one is really suseptible to someone adding all his/her friends just to see who they match - once you delete someone, the other person is no longer notified of the crush. plus, multiple people can match (downside) and there's only one type of relationship (the crush). and there aren't many fb connect sites out there: this is a good example of one.
then you are consenting to a relationship with whoever you match first. if you later say "oh, i didn't really mean to put you on my list!", its kinda like asking someone out and then saying "oh, i didnt really mean to ask you out!"
I totally disagree - there are lots of females who are lonely and want dates, and would be willing to try something like this. After all, lots of females use dating sites like match.com