Overall, it's pretty good, but I'm watching my flight right now (DL278, leaving in a couple hours)... Seatcounter has been showing it all zeroed in back and all 9's in front, but the seat selection map shows 3 seats open in back (in case I wanted to change to a worse seat for some reason...) so I'm not sure what to make of it.
Of course, it'd be nice if Seatcounter is right, and those three seats belong to people who just haven't been able to select seats for whatever reason. Or better yet, if there are, say, ten people who're booked in back and haven't selected seats... and DL needs to move some plats up on the last day before diamonds take over everything...
As of 1:10 before departure time, all seats in coach were assigned according to delta.com. I didn't get an op-up, though, so they must have managed load "just right" - or there were higher-LTV folks on the flight who got it. I did wind up next to the friend of the girl in 21C, who proceeded to trade seats with me.