Steve Mallett, in an article getting "digged" quite a lot lately, gives some reasons why Digg is superior to Slashdot:
"Hidden submissions. While everyone agrees that a filter to the front page is a good idea it does leave the question of whether the stories are legitimately refused. I'm sure most are legit, but...
User moderated stories. Slashdot has a 'flavor'. The editor's. That's cool. It is their site after all, but people obviously prefer their own flavor. If you don't like digg's flavor who's to blame?
The biggest boon of the open backend is that you don't have to wait to see that big story to approved by moderation if you don't want to.Comments. Flat threads appear to retard flamewars. You can also complete ignore some users. This was a feature if Kuro5hin originally I think. "
He makes some good points, particularly the value of users determining what gets on the front page rather than the owners of the website. I hope this means fewer stories on Star Trek/Star Wars and more on important issues instead (whoops, did I say that? :-). We'll have to see!