a few things I see that I'd kinda miss from delicious:

1) instead of seeing how many people are linking to something as a number, it instead has an "also shared by:" feature instead. I honestly like just seeing a number of how many people are sharing it more than seeing if a few random people are also sharing something. It also helps me judge whether someone linked a "big news item" or something they were personally digging for info on.

2) multiple tag filters - i.e. search multiple tags for my personal bookmarks. I don't use this much, but it's comfortable that it's there.