I know I'm gonna get modded down for this, but I was a usual reader at digg, and ever since I started spending more time on slashdot, I gotta tell you, it's a whole different level.
Digg is filled with "Take that sony!", "A kid got killed doing something stupid, humanity wins." one-line-comments; slashdot on the other hand, always has insightful comments, sometimes very interesting debates (I know, I browse only at +3).
To me, the most important part of slashdot is the comments section. A lot of useful information, specially on developers articles.
Digg basically only shows us the articles.