Digg finally implemented threaded comments yesterday, and the top story on Digg right now is a harsh criticism of the new system. The consensus appears to be that while the new system is a step forward in terms of technical functionality, it’s two steps back for usability.
New features on a large community site will always draw complaints from a vocal minority, so Digg may just have to wait a few days for these users to get acclimated to the changes. My personal opinion is that it’s definitely a good step to allow for true replies and threading, but the system seems over-engineered. Having to click to see any replies is a poor design choice, and with all the extra borders and headers, the page gets cluttered very quickly.
My unsolicited advice to Digg is to follow Netscape’s or Reddit’s lead and simplify what you’ve got. Drop the “click to view replies” links, keep the pagination (“Click to view the next 50 comments”), and get rid of about half of the extra borders and headers that have been added. Do this and you’ll get one of your famous “We love Digg for listening to us” frontpage stories, and the deluge of feedback e-mail I’m sure you’re getting will slow to a trickle.