At first you had to have the Entrecard widget above the fold, so I was considering dropping them. Now that they changed it and you have to have the widget one page down, it's better. However, I waste a lot of time with Entrecard and will be looking over my stats to determine if I get enough traffic to make it worth it.
Just went over my stats - totally not worth it in my case. I think there are so many blogs in their system that it's diluted the traffic because I used to get a lot more. I'll be removing my Entrecard code today and deleting my account. Too bad, because it was a cool thing at the beginning.