What I like is that they really did think about making the things work better that delicious had been strong at - quickly saving your bookmarks and recovering them - and not trying to turn it into something else.
For example, they could have expanded on the commenting feature, so that delicious would resemble FriendFeed a bit more. They didn’t. Commenting still remains an isolated feature tied to the bookmarks and not really allowing for interactions. I like this, because it will not change my current workflow of saving links in delicious and discussing them in Friendfeed.
Also the social networking features have not been accentuated. You can still send your contacts links with the “for:name” syntax, but that’s all. I haven’t been a heavy user of this feature anyway because I think it’s much better to just save the links and let your network select the links they find interesting for themselves. Or is there some magic application of this feature that I missed so far?
What I like very much is the visualization of the popularity of a bookmark. It’s simple and beautiful:
What I am missing is a similar thing for showing how long it has been a bookmark had been saved the first time. So I could see with one glance whether this is hot news or a reheated meme. And also: the ability to save bookmarks directly into one of my FriendFeed rooms. But this would be delicious 3.0.