I remember when it was good, but I don't really remember a time that there wasn't a fanatical vibe to it. The content there has always been strongly pro-Linux and anti-Microsoft. There was a time where people actually used the phrase, "Year of the Linux Desktop" without being sarcastic. Oh and writing "Micro$oft" was popular too. And there was always stuff about open source and GNU and GPL and etc.
The thing that made it good was the camaraderie, the general helpfulness, and the quality of posters. You used to be able to find some really intelligent content in the Slashdot comments, since some the smartest people related to that particular topic were probably Slashdot users themselves.
You used to find people like John Carmack in there... and electronics stuff was also talked about. Ask Slashdot's were answered with interesting insight. Now everything is mainly one-liners with stupid comments and only very few worthy users (eldavojohn and the like) remain.
If you are an active Twitter and/or HN reader you are already reading everything that is posted on Slashdot about two days before it is actually posted there.
Slashdot always had a large number of terrible comments (four digit UID here - right from the start the site had a huge troll contingent), however the moderation really did yield a better S/N ratio if you browsed the higher rated comments: On Slashdot you earned the occasional ability to moderate, with a limited ability to do so once you did. That resulted in more careful and considered moderation and I still believe it is an unmatched model.
I remember the days without trolls. (uid 872 here) The first one I remember showing up was meept. There's an entry for him on Everything2 dated Dec 05 1999, and it speaks of him in the past tense, so the troll-free days must have been few. I feel old.
Smarter moderation might work here in the short term, but ultimately the only thing that works is quietly sneaking off to a newer forum.