reddit is what you make of it. That's the whole point of different subreddits and the ability to customize what you see.

Once you get rid of the default subscriptions, the experience becomes way more enjoyable. Smaller subreddits generate less garbage and tend to be moderated better. Even better, you're less likely to see ads-disguised-as-content like you do on /r/pics and /r/aww. No one posts in /r/woodworking or /r/PrintSF because they want to whore some karma. /r/asoiaf has some wonderfully nuanced (if not repetitive due to the lack of new source material) discussions. And so on.

Overall, though, I think the state of /r/AskReddit gives the best summary of reddit's downfall. When I started going on reddit in 2009, the threads there were often interesting, and you didn't have to tag something "serious" to get serious replies. Several years ago, it began to be the case that if you didn't tag something serious, then, well, you would get thousands of comments of _literally_ the same joke. And that's default reddit -- thousands of comments of literally the same joke.