The only significant change I've noticed re: comments are how the nested chains collapse: instead of the intuitive [+] and [-] at the parent comment, there's a

The only significant change I've noticed re: comments are how the nested chains collapse: instead of the intuitive [+] and [-] at the parent comment, there's a line that runs alongside the chain. Click that line and it collapses. It's not as easy to figure out on your own, but it's a significant improvement IMO.