Digg was good back when it was mostly tech-oriented, before every other article was "GLEN BECK IS SECRETLY GAY" or "OBAMA: KENYAN SPY OR TERRORIST SLEEPER AGENT?" As popularity went up, incentive (and ability) to game it for stupid politics went up as well. Meanwhile, the website continued to get more ugly, less usable, and more like Facebook with every version.
The only reason I stuck with it until this week was that there simply isn't anything better. There still isn't, but now it's just turned into RSS+Facebook, and lost what value it still had to me.